Alright cool, thanks guys.

 

While we are on the topic, why don't you just knock out the cat and save yourself the finesse welding? Finesse for a welding noob like me, anyway.

 

As in just hollow it out? I would still have to take it off and weld it back on?

 

You'd have to cut it once before or after the cat, run a rod of some sort through it a bunch, and splice it back together. You could either clamp a little piece of i.d. pipe over the existing o.d pipe, or make just one weld.