Just installed my Invidia last night with the hlep of some friends. However, I do not know if there was supposed to be a gasket installed between the stock cat and the beginning of the Invidia B-pipe. I couldnt find one on the stock exhaust, unless it was already on there and I just missed it. TYIA.

How would I test for leaks?

 

There is a o-ring on the stock exhaust, but it only seals with the stock exhaust.

I bought a precut gasket from Spugen. PM AHHVTEC, he'll ship one out for a few bucks.

 

My Invidia came with a gasket.