My exhaust was around $260 in total. $230 of which was the Apex'I N1 Turbo canister. Highest numbers I put down were 179.1 and 178.3 whp and 125.3 and 124.8 tq. It was SAE corrected, done in 4th gear, and temperature was 75 one day and 84 the other. Humidity was around 50% and 78% respectively. Only other mod was Injen CAI. Dyno's are posted on this forum, just do a search.
Looking at the dyno run list, the only people who dynoed more than me N/A were Larry and he was running in 34 degree temps, while I'm in South FL. Jim aka Icyjaws ran less than me with no muffler, but more with no a/c and power steering.
Paying for a pre-made exhaust doesn't always pay. Myabe I just got lucky with my setup, but I know I'm making the power. Considering I did run a 14.4 with a 7800 limiter as well. Just my .02 cents.