I just got a GReddy Global Sport G2S exhaust system installed in my '03
A4 1.8t by Syizm, authorized GReddy Dealer, in Lake Forest, Ca. I had been suffering from low end lag off the line (below 3k rpm), so much so that the car would shudder & stall at times. It was such a pain in the ass.
My buddy Marshall at GReddy suggested the exhaust upgrade and boy was he right! It smoothed it all out and the car is way more responsive. Sounding great to boot! It was not as loud as I thought it might be. I highly recommend this upgrade and this shop.