A friend of mine has twin 502 MPIs procharged in his 32AT. The Prochargers are 18 yrs old. A few questions. #1 Do they require rebuilds like a roots type blower? #2 If you install a smaller pulley for more boost do you have to re calibrate the ECU or make any other adjustments? He has called procharger regarding this but can't seem to get any definitive answers from anyone at the tech desk. Is there someone in particular there he should be talking to? Thanks

I'd contact articfriends on here. He's pretty intimate with Prochargers and EFI tuning.

Yes pro chargers do have bearings and do need rebuilding from time to time.pro charger will not sell you the parts to rebuild but will gladly rebuild them for you.i got some parts from someone other than pro charger to rebuild one and the parts were pretty much junk.

Yes they can be rebuilt but hold up amazingly well if maintained as recommended. You can add the smaller pulley for more boost. I would re-flash the ECU any time you make a major change to an EFI motor.
AZ Speed and Marine does them, all you do is give them the specs of your motor, etc. and they flash to a similar build. I'm sure others will share their thoughts.

. Is it just the bearings that wear out or is there seals or something that wear and leak by and cause reduced boost? thanks

Reduced boost could be the intercooler clogging up, could be belt slippage,

Prochargers DO need to be rebuilt, i had a m-3sc, called procharger, said i thought it needed rebuilt soon. I had 220 hours on it, turning it pretty hard. They said naw, i was fine, wait till 400/500 hours. A few weeks later it let loose and self destructed. I should have just sent it in and said do it anyways. They got like 950 to redo bearings and seals, and 1850$ to totally redo with impeller, shafts etc 10 years ago. Not sure today

As far as tune, IF your using a mefi3 and it was actually tuned in ecu, the boost tables end at 150kpa. If your running close to that, because table's dont have as much resolution as a mefi4 tuners end up adding fuel at 100map/kpa in certain rpm bands to get afrs right under boost. If you go higher than 7.35 lbs (150kpa), you need someone to go in and add fuel at that point and retune it . Your stuck with whatever they put in there too since it doesnt go higher. Mefi1 is MUCH worse!