we have a dyno tests. I will post them when I get back from Cali. 3in dp and N1 exhaust (90mm) vs 4in dp and hks ti on a t88h. 65rwhp difference. And about 700 rpm faster spoolup on a 95 supra. (FYI: the t88h has a 4in turbine discharge) The HKS sounds badass btw, very loud though. Sort of like a straight exhaust with a huge resonator.