Looking for a quiet cat back system that is pretty free flowing, but noise is an issue at track days, so I need something pretty well silenced. I have an unknown make system on my R33 GTS-t that has 2 pipes into the back box, it's perfect EXCEPT the twin pipe layout is stopping me using the GTR subframe reinforcement cradle that i want to bolt on to the car. The cradle catches on one of the 2 pipes, so a GTR system is needed. It doesn't have to be stainless, have a massive tail pipe or look trick, just be efficient and quiet. Thanks.