I recently just got a DC 4-2-1 header for my car, but i have an exhaust leak coming from the stock donnut gasket between the header and the cat. Has anybody else had this problem before, if so do I need to get a new gasket?

 

your CAT is actualy about 3 inches after the exhaust comes out so if you got some DC headers you dont really have a cat any more.........the resinator is underneith the car which looks like a little long can...... so you might be thinking that is you cat

but one rule of thumb is to be safe than sorry and always replace gaskets....

so yes replace the gasket

 

The cat coming off of the exhaust manifold like you are talking about is only on the dx or non-vtec models, I have an ex model so my cat is under the car right after the header, then about 2 feet later comes the resinator. I am not that dumb, but thanks for the help any way.