I'm currently running the JDM DC 4-1 and Carsound 2.5" cat with SMSP's hardware and donut gasket. I've noticed that the header/cat connection may be a potential source for leaking. For some reason, the header/cat connection is a bit angled. The header seems to be angled up a bit, while the cat is angled down a bit. The "bottom" part of the connection is good, however, the "top" is not. The "top" of the cat flange is barely mating up to the donut gasket. I've tried making some minor adjustments with no improvement.

Would using a slightly wider gasket help out? Is there a 2.5" donut gasket that is wider than the one supplied by SMSP?

Thanks,
Chris

 

You're going to have to contact Dave about the gaskets.

That area is a place where there is some play. Is anything bent slightly?