The test was twinz300. You can check his profile and that was a change from gutted main cats, gutted precats. The biggest gain was also from the 3PSI gain in boost. He couldn't get past 18PSI with his old stuff. Those down pipes are the best and the high flow cats aren't bad.. But I rather go with high flow test pipes :-) He maxed out those tiny T28s at 450RWHP or so.