I put on a new exhaust, cat back, this past weekend. I have two leaks, one where the front pipe connects to the cat and one where the front pipe connects to the manifold.

Questions:

1. The connection between the cat and the front pipe: There’s no gasket there, right? I had ordered a gasket (“Front Pipe Gasket: Pipe to Converter” from fcpgroton) which looked like a metal donut, but the back of the front- pipe was rounded and fit into the front of the new cat, when I tried to put the gasket in there to see if it fit it didn’t look like it belonged.

Here is a picture of the back of the front-pipe (before removing the bolts from the flange):

http://tinyurl.com/8emgh

The obvious leak here is where I cut through the front pipe a little when taking off the old cat, you can kind of see it in the picture as the clear metal an the far left part of the inside of the pipe. I was going to have that welded shut which leads me to question 2:

2. Is there anything inherently wrong with just welding that connection solid? The connection between the back of the front-pipe and the front of the cat. It’s a new cat on a 13 year old car with 150,000 miles, surely I won’t need another cat, and the front-pipe is still in good shape so I don’t think that that will ever need to be replaced.

3. Where the front-pipe meets the manifold I have a really bad leak. There’s a metal flange with three bolts. Is there a gasket in there? I see references to the exhaust manifold gasket in the FAQ – is that gasket between the manifold and the heads, or the manifold and the front-pipe?

Thanks!