Rather than posting a recommended 3800 supercharged modifying roadmap, which maybe 5% of people who read will follow, I’m going to post some general outlines and tricks and tips, which I recommend to those who ask and mention to those who need to know.

Cams

I have specced and had success with my own 3800 custom camshafts in past. While I will no longer carry these camshafts, I will provide info on them including how to order directly from CompCams.
Overkill SBC (Stock Blower Camshaft)
214/224@.050 duration, 134/141@.200 duration, .507/.507 valve lift@1.6 rocker ratio, 116LSA, 114ICL

What It Is: A healthy duration cam that easily fits stock heads with minimal additional supporting parts.
Why It's Good: Designed to be reliable using more of the factory valvetrain than competing camshafts, saving money and removing reliability variables. Duration is larger than the typical/popular cams, will provide the full horsepower gains you expect. Tell Me More: Will- I designed the SBC camshaft for a typical M90 build with stock heads. This cam is very right sized. There are good cams on the market but the larger offerings require consideration of a double roller timing chain, double front cover gaskets, milled oil pump covers, milled retainers etc. Here's something that I've learned from experience: more aftermarket components do not make a more reliable setup. This SBC cam can be run on stock timing chain and tensioner, and inexpensive and reliable GM valve springs and retainer caps. Not only will the setup be more affordable, you lose nothing in terms of performance.

Timing chain and tensioner concerns are greatly lessened with using a .500ish lift and 90# GM valve springs. Both the LS6/LS3 and the LS4/L92 774 springs are rated 90# seat pressure, however the 774 springs have a lower spring rate, meaning as the valve opens and the spring compresses it won't be as stiff. These springs will be easier on the chain tensioner than the 224 LS6/LS3 springs, however I've used both with the SBC cam and factory timing set with very good long term reliability.

Although slightly lower peak lift (specs you see), the opening and closing rates are faster than typical cams (specs you don't see). .200" lobe duration is an important spec, rarely talked about. I go into more detail below but the bottom line is despite seeing a lower overall peak lift, this can will hold close to its peak lift for a longer duration, that's why it'll perform. Shorter duration below .050" at the base of the cam profile means better fuel mileage and idle quality. Minimized overlap and ideal intake valve closing event means strong midrange torque and great cylinder filling at higher engine rpm for strong peak horsepower figures.

300 wheel horsepower is easily attainable without an intercooler when combined with good tuning, quality headers, 3" quality cat-back exhaust, larger fuel injectors, and on a Series II 3800SC either a ported supercharger or a swap to a Series III GenV M90 swap with a 75mm throttle body upgrade.

You can upgrade this camshaft with 1.7 rocker arms, even on stock heads. By installing those previously unnecessary supporting items such as a double roller timing chain setup and milled valve spring retainer caps, a 1.7 roller rocker arm will further increase the opening and closing rates of the valves and provide a .537" peak lift. 1.7 rockers provide up around an additional 10 wheel horsepower gain with this cam and make it perform like a camshaft ~10 degrees longer in duration.

When this cam is the right cam for you: If you're in the market for any of the typical cams that run on stock heads, this is a cam for you. It can be run near stock on a basic rebuild where you just want a cam to upgrade while you're in there. It can be run on an intercooled, headered, 2.x" pulley build and deliver great results. Idle quality is good, you'll certainly hear the camshaft through the exhaust but it'll be smoother than you expect because the base of the lobe is actually 5 degrees smaller than the slower opening/closing rates of other cams. You'll simplify your setup, you'll save money, you'll have fewer doubts about the longevity of your setup and whether you found the right parts mix, this is a great camshaft I believe in highly.

Overkill BBC (Big Blower Camshaft)
224/234@.050 duration, 141/148@.200 duration, .507/.507 valve lift@1.6 rocker ratio, 116LSA, 116ICL

What It Is: An extended duration cam that is designed to work specifically with Rhoads variable duration lifters. Easily fits stock heads with minimal additional supporting parts.
Why It's Good: Designed to provide maximum horsepower gains. The largest camshaft that will fit onto stock heads. This cam/lifter combo will provide good street manners, good throttle response and torque, while providing high horsepower gains in the upper rpms when needed. When combined with 1.7 rockers, this setup should outperform anything on the market on stock heads.

Tell Me More: Will - The BBC camshaft is designed to be big but manageable, and be plenty compatible with factory cylinder heads.Larger camshafts often provide more harm than good on supercharged setups. This because you either have excessive overlap which hurts performance under boost, or if you widen the lobes apart you now have less ideal exhaust opening and intake closing events which hurt torque and throttle response.

This cam is designed to work with the Rhoads variable duration lifters, to combat these issues. Rhoads lifters work similarly to AFM/DoD lifters. At lower engine rpm, the hydraulic center plunger that supports the pushrod bleeds off its oil pressure and collapses during the movement of the lifter, taking up some of its movement rather than translating it through the pushrod to the rocker arm and to the valve. As a result, peak lift is lower and the valves close sooner. Between 3000-4000rpms, the lifters physically do not have enough time to bleed down anymore, and now provide the full lift and duration of the camshaft. And because the duration is taken off of the closing events, it also has the effect of advancing the camshaft, which will provide better throttle response out of boost, while the cam is specifically designed with later closing events which now occur only at higher rpms, to promote better exhaust evacuation and better cylinder filling from boost. These aspects cannot be done with a non-VVT camshaft and with regular lifters, that's why this cam designed specifically with Rhoads lifters works so well together.

When this cams is the right cam for you: When you're interested in maximizing your possible horsepower gains, this is for you. If you don't mind a little unorthodox, this is for you. If you don't mind a little lifter tick, these lifters have a very distinctive solid lifter like noise, this is for you. Unlike the most popular cam choices, there are no double roller timing chain, valve spring or modified retainer debates required and while you spend on the lifters you'll save that or more by not purchasing unnecessary supporting parts.

.200 duration specs
People get fixated on max lift to determine how well a cam will flow, simply because it's a spec that's always advertised. A better way however is to look at the .200" duration spec. This spec is importantly yet rarely given. Look at any head flow chart and you'll notice how much the flow improves at .300" valve lift and above; the longer the valve stays above .300" the more power the cam will allow the heads to make. Old V8 engines ran 1.5 ratio rocker arms, and .200" cam lift times 1.5 rocker ratio is .300" valve lift, that's why .200 duration specs are important and given, if you look for further details beyond the advertised specs.
.200 Duration:
Why more aftermarket valvetrain parts don't lead to a more reliable build

A common item to install is a double roller timing chain. The main purposes this serves is eliminating the factory chain tensioner, which is prone to wear with stiff valve springs, while the chain itself is supposedly strong but in reality I haven't seen evidence of that. Here's an example of a Rollmaster double roller timing chain with a few miles on it, note the slack in the chain with no tensioner now to take it up:


When this happens, it's possible for the chain to try and skip a tooth, and in my experience I've seen Rollmaster gears chip a tooth or two, requiring a replacement, after roughly 3-4 years of service time.

I commonly used JP timing sets roughly 7-10 years ago. In my experience, at the time, they were better because a) they used a stronger chain than Rollmaster and b) the gears themselves appeared to be made of a stronger metal. I've had these sets in my engine builds now running 5+ years without issue, 7+ in my former GTP now being enjoyed by a new owner. In the meantime, this has now happened, and JP sets aren't considered a viable option http://www.clubgp.com/newforum/tm.asp?m=4752021&p=1&tmode=1&smode=1 Rollmaster units are now considered

Other issues arise. The JP and Rollmasters were designed for Austrailian 3800 motors and don't have the proper chamffeur at the back of the crank sprocket. As a result, the chain sits too far forward on the crank when installed. This is why it can contact the front cover, the crank sprocket to the oil pump cover and cam sprocket to the upper area of the front cover itself. The crank gear pulls the cam gear forward in order to achieve alignment and Ive seen cracked cam retainer plates as a result, that's how extreme it is. I'm sure this misalignment has something to do with the chain stretch as well. Bottom line, you need to take the crank gears both stock and Rollmaster to a machinist and have the Rollmaster machined to match the factory. During install you need to use a straight edge to ensure the gears are properly aligned without the camshaft budding against its retainer plate. Intercooling
It’s never too early to intercool. Hear me? Never. I’ve tuned vehicles with factory manifolds and downpipes and Ubends, with an intercooler, running a pulley size that they’d need a full compliment of Bolton parts to otherwise run. Not only were the vehicles quick but if you are reasonable in expectation with your expectation of what pulley size you can run there’s no knock and you won’t encounter any with continued reasonable expectations and good tuning. Ensure you run a good quality pump. ZZP and Frozen Boost both sell quality Bosch pumps. These pumps can be run without a relay system, just use an add-a-fuse circuit within your factory fuse box under the hood in a switched fuse, and then run a separate ground.
A reservoir is ideal due to added capacity, reduced aeration/cavitation from the pump, but sometimes hard to fit. The 2004+ coolant reservoirs have lots of angles and flat surfaces where you can drill, add a rubber grommet and fit 3/4” barbed fittings for in and out to turn it into an IC reservoir as well. The 04 bottle can be retrofitted to 97-03 GP easily. Have the pump suck directly from the bottom area of the reservoir; once pumped through the rad and then the IC core, I run a 90* beneath the alternator and 90* again along the firewall directly back to the reservoir.

MAF sensors
On 2004+ Grand Prixs, any 00+ 3400 Impalas/MCs, any LS4s and any Northstar throttle body conversions, all of which have inline separate MAF sensors, the orientation of the MAF sensor is VITALLY IMPORTANT to its proper reading.
On all the above except the latter, refer to how the MAF sensor was oriented from factory, and keep that orientation! Rotating it around will affect its airflow readings, and affect how accurate your MAF calibration is.
On the latter, the LQ4/LS6/”85mm” and however else you wish to refer to it MAF should be oriented with the flange facing to the 9 oclock position, making the wiring connector face to roughly 8 oclock.
On 2004+ Grand Prix supercharged, you’ll max out the factory MAF readings at around a 3.4” pulley. Even before then, its small size is a restriction. Consider the MAF upgrade that’s listed on this website.

Fenderwell Intakes
A fenderwell intake is the only way to properly get cold air to the engine. You must place the air filter outside the engine bay to suck in cold air properly, encapsulating the filter rarely works as well as its theory. There are instructions all around the internet forums on how to set this up but what I will do is give a warning that you must must must keep the air filter clean in order for there to be a benefit of cold air introduction. The filter will get very dirty very fast down there in the fenderwell and once dirty you will negate almost all of the benefits of the cold air by restricting airflow to the motor. There is benefit to cold air on a supercharged vehicle, however do consider an underhood open cone setup if you’re not committed to proper FWI filter maintenance, I sell such setups on my website.

Spark Plugs
A spark plug has two jobs. One is to fire the cylinder its installed into. Second is to remove heat and maintain a proper operating temperature in the cylinder, which many people don’t realize.
All 3800 Supercharged engines run too hot a spark plug. They run the same very hot plug that the non-supercharged 3800 run and even those are hotter than most other GM V8s for example. Even fully stock with a stock pulley, it is my strong recommendation to drop one heat range, to an NGK TR5 or other plugs that you can spec from a GM Vortec/LS1/2/3 V8. When running a smaller supercharger pulley such as a 3.5/3.4/3.2, its my recommendation to go two heat ranges lower, to an NGK TR6 or Autolite 104 for example. If you’re running a full supercharger build with a 2.55” pulley or a turbo setup with more than 15psi of boost, you can now step down again to NGK TR7s or Autolite 103s, however this step is only beneficial on extreme setups, I would stick with 2 range colder on the majority of setups and ensure your intercooler is doing its job to remove heat from the boost.
Copper plugs have a wider centre electrode and they will run cooler than the sharp thin pointed Iridium plug centre electrode. This can lead to reduced engine knock. They will erode faster though, and require replacement or regapping every year. Run copper plugs only if you truly mean to take care of them, they are not a set and forget installation.
Speaking of gapping, it’s my firm belief that most run too wide a spark plug gap. Factory gap is an outrageous .060” and the ignition system is strong enough to handle it. However on supercharged 3800s I recommend a gap of .050” on stock pulleys and .045” most smaller pulley setups. Full bore setups with 2.x” pulleys should run a .040” gap. Minute misfires that you may not be able to fully feel can show up as KR on a scantool and closing the gap can reduce this KR when it occurs. This is contrary info to what you read on the internet forums but this is a lot of personal experience being given here, do not run a gap that’s too wide, even .040” is plenty of gap.

Power Steering Fluid
Most 3800s have steering system issues because no one knows where the reservoir is (its below the alternator at the back of the engine btw), fluid gets low and the pump whines like crazy. But also, its not uncommon to see very murky and burnt fluid in the steering system. Its my recommendation to switch the steering fluid from GM steering fluid to transmission fluid. Many other manufacturers run trans fluid.

When to do a 3” exhaust
On nearly any smaller supercharger pulley setup, its always been my experience that the vehicle has less KR issues if they run a 3” downpipe with a 3” cat-back exhaust, and I must conclude from this alone that a 3” system is beneficial at nearly any mod level. As a rule of thumb, I generally say that whenever you do headers in particular, do a 3” cat-back. Not only are headers one of the best mods you can do on a 3800 Supercharged engine, a 3” cat-back makes the most of the headers and will support future modifications appropriately

When to do a GenV M90 swap
The GenV or Gen5 M90 is from the Series III Supercharged 3800 on the 04-07 Grand Prix. It Is an upgrade for the Series II motor, producing more boost per pulley size. So when is it beneficial to upgrade? My answer has to be when doing an intercooler, for a couple of reasons. First, the Gen5 unit makes the most difference over the Gen3 when the pulley sizes get smaller than a 3”. Second, in order to get to those pulley sizes, even on a heads/cam motor, you’re best off running an intercooler. And Third, intercoolers are gen specific, so you can’t necessarily buy a gen3 core and then do a gen5 later, so do them as a pair and get a gen5 core.

Performance Spark Plug Wires

First rule of performance spark plug wires: don't buy performance spark plug wires. These wires are often touted as low resistance and more heat resistant and will last a lifetime etc. I've had far more success using quality factory plug wires, the kind that I sell in my parts section which is an OEM brand that came from factory on the Series II 3800. The main reason I like factory wires is build quality, because poor build quality can negatively affect performance. I want a wire that doesn't fall apart the first time you disturb it, makes positive electrical connections at its terminals and lasts a long time. Here's a few examples of what goes wrong in my history of performance spark plug wires: