new guy on the block here, i need some info/suggestion on what size */c pulley i should change to. i have a 92 ssei, the stock pulley measures 2.5in were the belt rides.
current mods to the car include a 3in exhaust minus the cat, and a dynomax welded muffler, future mods will include a cai, also do i need to rechip the pcm to take advantage of the smaller pulley.
i must say its great to find a bunch of guys that know and appreciate these great cars most of my friends think i'm a little wacked cuse i really like my ssei,

With the exhaust work you have plus the cai you have planned I think you could get away with a 2.2" pulley. The custom chip will remove some of the limiters and allow for higher shift points.

Your exhaust is opened up plenty for a pulley. You will definately need the cold air intake. Most of us here make our own. Make sure you also put in the 180* thermostat and its not a bad idea to drill it in my opinion. Then another must is colder plugs, go two heat ranges colder, most common ones used are the ngk tr6 plugs. I would definately go with the 2.2" pulley from pulleyboys.com and then get the oversized belt tensioner from zzperformance.com along with some stock length gator back belts. These things should put your project well on its way. Oh and the chip is not a necessary item for the pulley but after you get some more mods done a chip would help. I think hypertech makes a chip for your car and possibly jetchip, but thats after the pulley. Hope this info helps you out.

oh and one more thing, how many miles are on the car? you might need to replace your coupler in your supercharger and you want to do that before the pulley. If its bad you will hear rattling where the snout of the supercharger bolts to the body of the supercharger.

Your exhaust is opened up too far for even a 2.2" pulley. You would have been better sticking with the 2.5" exhaust. Every car here that'* tried 3" exhaust has lost backpressure and low-end torque.

3" requires some SERIOUS modding to support it. You may have opened up the higher rpms, but you did lose low end, which is what our engines were built for.

I beg to differ somewhat. After driving SSEi95'* with a pulley, 3" exhaust, and such it pulled damn hard. This is without a CAI....

A lot of 3800 F body guys go to 2.75 or 3" and only loose marginal torque. Infact the "Feel" of lost torque can be due just to the smoothed out power band from the opened up exhaust. However keeping a regular cat and a muffler that have have some backpressure may give you some tuning. Or a pair of tunable mufflers.

Again the only way to conclusively know is to dyno with 2.5, then dyno with 3.

I beg to differ. You're comparing an L27 to an L67. Gordy told me himself on IRC last year that he probably lost some low-end with it. You say that alot of Fbody guys lose torque with 2.75"? Think about it. I took this subject to an expert, and it was discussed at Tech Day for WCBF with 2 gearheads in attendance. 3" is just plain too big, unless the only thing you care about is horsepower, and ignore the torque.

Any L27 that attempts this will be sadly disappointed, and most MILDLY modded L67'* as well.

How many FAST cars are still running on 2.5"? All of them, except a couple extreme examples.

well if i went to big on the exhaust i will have to live with it. but after many years of hot rodding cars one of the first mod is free flowing exhaust, if the oem exhaust is 2.5 than logic says 3in would be better if i want more flow, to make more power i need more air/fuel in so i need to get rid of it thru a higher flow exhaust, but this is the first time i've delt with a */c engine. i will admit that it lost some of the initial hit of the */c, what are the down side of going to a smaller than 2.2 pulley?
lets face it all oem engines are made for low to mid torqe, because that is what gives you that seat of the pant feel of accelleration, but most of these engines start to fall off above 3500 rpms, becuase joe average doesn't drive above that to often. to make more power you do useally give up that low end but gain more in the mid to upper.

Most of the cars you're familiar with probably don't have the low-end punch that a SC 3800 do, and many of them were probably V8'*? This is a totally different world now. Your engine needs something to 'push against', and it'* called backpressure. You already felt the results with your low-end loss you just described.

If you go smaller than a 2.2" pulley on a 92 or 93 (or smaller than a 2.5" pulley on a 94/95), you'll create too much heat, lose boost as the M62 is operating WAY beyond it'* efficient range, and induce KR in a bad way. The only way you could go to a 2" safely and effectively is to intercool. Nobody makes an intercooler for the Series 1, which leaves you with water injection. WI is not an effective "everyday use" solution.

I'll have to agree with Bill on this one. I, like you, came from the world of hot-rodding, mainly pre-1980 V8'*. 3" is perfect with those. I had to relearn and rethink when I moved to supercharged V6'*, especially when taking into consideration today'* newer standards. When I did the math, however, it held true. What makes these cars fast is the torque, not the horsepower (so much), and the trannies and differentials that get that torque to the ground.

Bottom line: Too free flowing is bad for SC'd 3800'*.