I'm hoping that somebody will know a part number or a diameter or something regarding swapping out my alternator pulley to overdrive it. I have a 95 non-supercharged 3.8 but put the 140 amp alternator in from a supercharged 3800. I have a decent amount of juice for my amp with the 4 yellow tops in the trunk, but i want to make sure i keep enough juice for the rest of the car and i figure overdriving the alternator would help. Any ideas please let me know.

Take a look at this, it should work on your car. Got me about .75 more volts from my alt and costs under $10 to do.

https://www.gmforum.com/t278155/

Otherwise, here is a pulley.

ZZ Performance

Being a speed demon, I would worry about overvolting my electronics by overdriving an alternator. They dont last long either exceeding the speed the bearings/sleeves are engineered for. 200 amp alternators are available, not that expensive, replacing is no harder than swapping pulleys, and the right way to go about this problem. I see this type of situation all the time at the custom shop with alot of fried electronics (Not using enough amperage source, right fuse blocks, capacitors, crossovers, batteries . People lay out wads of money for amps and speakers, then dont dot the i'* and cross the t'*.

as of right now i swapped in a 140 amp alternator from a super charged 3.8 and it'* workin pretty good. I have my house battery in the engine bay which i'm going to switch to a red top very soon, than i have my Kicker 0 gauge running from that battery to my 4 Yellow tops in the trunk. It'* working quite nicely now when i'm cruisin down the road, my battery needle barely moves. When i'm sittin at a light it'* gonna move obviously since the alternator isn't putting out enough. i haven't found a cheap 200 amp alternator anywhere which is why i'm goin for a smaller pulley for now. If the alternator dies, i just swap it at my store and get the warranty. If you have any ideas or suggestions on where to get a 200amper let me know, i'd much appreciate it.

Check your ware comeing from the alt. Is there 2 wires, or do you have 3? If you have 2 then folow that link I posted above for a sense wire. It will get you another .75 volts. About .5 at idle.