I have a completely stock Bonneville SSEI 1999 how many pounds of boost does the supercharger create? and if i buy an upgraded supercharger pulley what else would i need to complete this upgrade? I also hear that for every .10 of an inch smaller in pulley size you get 1 pound of boost...is this true?

Welcome to the bonneville forum.

Stock you will get about 6 or 7 pounds of boost from your 3.8" pulley. I suggest you only drop to a 3.5", no smaller. This will get you around 9 pounds of boost. To go smaller you will need to make soem changes and also scan for KR or you risk damaging the engine.

Yes, a general rule of thumb is 1 pound of boost for every .1 smaller pulley. But you will need the supporting mods to do this. You need to change your intake, and do some work on the exhaust.

So can i keep it complete stock and just put the 3.5 inch pulley on it?

and do you know what kind of horse power boost that would equate to? Just a guess would be great.

Every car is different, but you shoudl be safe with a 3.5" as long as your running 93+ for gas. Figure 15 or so HP. Changing your air intake to a gutted air box will help a little as well.

XXALPHAXX - Pay particular attention to what Dan said about the Hi-Octane gas. You switch the pulley, you need to up the fuel octane to 92+. Running lesser grades will ruin your MPG, performance and can result in some engine damage from ping/denotation.

Another thing to keep in mind is boost is relative.

If it'* cold out the air is denser and you'll see more boost. If you are at a higher altitude you'll see less boost. Dan'* the man and on the money for the average though.

And if there'* one thing I've learned and think should always be said. Try to get away from measuring boost, beyond yes it'* there and reasonable. Boost is the pressure in your intake manifold. This pressure can be increased, much past 11-13 and it'* simply pressure in the manifold and stacked up energy you can't use. Which means it'* creating power robbing heat for no reason.

Flow mods like headers, cam, rockers, ported charger etc will reduce the psi in the manifold because it'll flow through the cylinders. Flow = Power.

Having less boost and more flow can mean you have much more power.

Bill is very correct. I have 13.9 pounds of boost, if I removed my headers and rockers I'm sure that would be over 16 because it'* backing up. Flow is the way to go.

So now you guys have me thinking...Would it be wortless to upgrade the pulley until i got a better intake and a possible few other things...OR would it be just a quick and cheap little "pick me up" for the car something to just give it a little kick in the ***?

Many folks drop a better intake in place, or gut the airbox and use a K&N filter then put the pulley on.

Thing is..and now that I've been there and done that..boy did I take the expensive route.

I gutted the airbox and got the K&N ($55)
Got the pulley ($127) with a puller. You'll need to rent or borrow the puller as it'* specific to charger pullies and you run the risk of killing your charger with regular pullers.
Then I got an MPS pulley system ($100)
A couple more pullies ($150)
Some changes to the intake ($50)
Ported Exhaust Manifolds ($280)
See how this is going? Had I thought the car was going to get modded like it is..I would have sat down and planned the mods to keep from double or triple spending on the same types of things.