Lots of good questions here. Like I said I'm running 18.5 psi and I ran the car yesterday in 105 degree heat all the way through 4th gear several times with no knock. After 6k in 4th I'm pushing over 19psi boost as well. Timing is about 20 degrees currently due to the heat. It is pulling full advance under WOT. Duty cycle doesn't mean much really, because you can be over 100% and still be ok. Alot of it is how you scale the fuel delivery before WOT. I've customized my timing ramps and injector flow to be able to run lots of boost with the 42's no problem. The car maintains an A/F ratio below 12.0:1 all the way to 7k in 4th gear according to my dyno testing.

Also, the M62 is good to about 17,000 rpm's intermittently as has been posted in another thread here somewhere so no worries. I wouldn't go smaller than 2.5" and 7k limiter otherwise the blower will be toast. Personally, I didn't want to machine the snout so I went with the pulley in my sig. I'm running the BKR7E's at .035" which is the stock gap. Don't be deceived by the spark plug threads because that is the gap you want no matter what pulley size you run - especially if you are down south in the heat.

The gas I get here is 93, but it is 10% ethanol. As has been noted, our cars run 58psi fuel pressure so the 42's are pretty stout. They will handle 275whp with the proper tune, which is a limit I do plan on testing. It's all in the tune folks. After the blower and tb are ported I have no doubt that I will be seeing 20psi - in fact I expect a little over that. Then - that's it - because this is my girlfriend's daily driver. I just hope the clutrch holds out

Chris