One of my biggest complaints was the exhaust note, we removed the cat and it sounded bad, we then removed the centre muffler and it sounded like ass! So in the hope to recover the nice RB note the car is now fitted with a HKS dragger, i have heard these can be restrictive and due to that i have run the 3.5in system which looks to step down after the rear muffler, it should flow the same as the old one but it sounds real nice, deep yet quiet at idle again -