I have definately experienced surge on the stock turbo

 

The only time I had that issue with my stock turbo is when I was in 5th gear on the Parkway and I was at around 5000rpm (lil over 100mph) and whenever I got on the throttle partialy it was sputter and surge...

 

Yeah I can get my 03 to surge on command. I would immagine a larger compressor cover would aid in any surge by adding lag.

 

The surge is definately present but there are ways to alleviate most of it. First off, is driving style. The turbo will surge for me between 4k-5k if I am in a higher gear where the engine is bogged down and is slowly building boost. I experience little to no surge if I am in a situation where the revs are high and I am shifting gears. The spool is somewhat laggier than stock, but I am still able to build 20psi around 4k. I am installing a clutch/lightweigt flywheel which should help this some. Another way to alleviate this surge is to loosen the BOV to allow it to release pressure more easily. Dave mentioned that he is working on something that will eliminate this surge and hopefully increase power so we shall see. The turbo feels good, but it is hard to say due to the fact that my stock clutch is slipping. I am hoping to hit the track when the clutch is broken in and AMS is having a dyno day at the end of the month that I will attend. I feel this turbo has good potential once the bugs are worked out of it and people's setups are done right