2.8 b5 supercharger
 

I have a guy that did all of the math for me and with a pes g2 supercharger, methanol injection and a bullet inline water to air inter cooler he got about 600 horsepower. I trust his math. I want to know what else would need to be done to handle that kinda power

I would think a blower pulley about 1/3" in diameter. The 2.9" overdrive pulley allows 12psi and makes less than 350hp with breathing mods. I HIGHLY doubt a G2 can efficiently put out enough psi to make 600hp...

the guy

...is full of shit most likely.

I've known the guy for most of my life and he has 30 years of performanc modification experience. I didn't post it so you could say the people I know are full of Shit I wanted to know if the drivetrain could handle it that's all.

I reread your question and when I read it the first time I took it to mean he had these parts in his car and was claiming 600hp, which is why I said what I said, so I apologize for misunderstanding what you were saying.

On point though, I don't see it happening. It's a small engine and a small blower first off, and I don't see how you could spin it fast enough to make that kind of power. The limitations of its flow and superheating the intake charge are going to come into play - you're talking MASSIVE boost pressure.

But going on the stretch that, if all other factors were in place, that it could build enough boost without melting, you'd need to build the bottom end, you'd want cams, most likely head work (although some of the S4 guys swap out to 2.8 heads for big boost applications as the ports are larger than the ones in the 2.7T), definitely an upgraded clutch/flywheel, axles if you plan on launching the car hard, upgraded engine/trans/diff mounts, an AWE drivetrain stabilizer, and at that point you'd probably be ok. The last piece, in addition to this and what you mention in your first post, would be standalone engine management and full dyno tuning.

Physics being what it is though, I don't think the G2 has the ability to move enough air and pressurize enough for that kind of output - you'd need to look at a bigger blower and build the car from there.

ImTheDevil (or anyone else) - On the G2, what is the maximum BHP you think is possible (with the mods mentioned by the original poster)? Also, if doing a pulley change, what size would you recommend to balance maximum performance with life of SC and Engine? Lastly, would you recommend adding an intercooler to the PES G2 (on the 2.8)? If so, any thoughts on the best direction to look for the 'right' IC mod/kit?

Hard to say. There's a 2.9" overdrive pulley available that raises the boost from 8psi to 12psi and is said to add around another 50hp. Intercooling is not possible - the G2 is incorporated into the intake manifold. The G1 blower could be intercooled as it sits where the airbox is. The problems you run into are volumetric efficiency of the engine and the fact that the off-the-shelf tune leaves a lot to be desired, so to do it right (even on the 8psi pulley in a basic application), you need a custom dyno tune. The proper way to spell that is M-O-N-E-Y. Ask yourself if that much time/work/cash is worth it to hit maybe 350-400hp on a 14 year old car that sells for $2000 these days, when an S4 can do it with bolt-ons for a fraction of the price.

2.9 pulley
 

I did just order a 2.9 pulley. My B5/A4 just rolled over 100k a few months ago before the wife cracked the upper oil pan hitting a dip. I was out of country for a few months so just getting around to the fix. While we are in there doing new Stage 1 clutch, brake kit and a whole bunch of other stuff if there is any work that we should do on the heads or on the lower engine while it is out I'd be curious to know what people would recommend. Also it has it snow performance methanol injection and was curious if we should do any upgrades to the meth injection.

2.9 pulley
 

It's my understanding that the 2.9 pulley only raises to 9 or 10 psi and that it is the 2.8" pulley that raises the boost to 12.