Welding/making a catback

[jononumber5]

I recently got a nice blue P5 (thumb). I wanna get a bit more hp and add a few things but on a budget. Im a really good welder and I wanted to just buy a muffler and some 2.5 or 3 inch tubing and make a catback. Has anyone done this before? Or have any ideas suggestions? Thanks.

[mountjonas]

i think people have gone to shops for custom catbacks.

isn't 3 in. too big for for this car?

[jononumber5]

i think people have gone to shops for custom catbacks.

isn't 3 in. too big for for this car?

Yeah 3 probly would be too big, 2.5 is probably best although I haven't checked. But basically I just wanna save $$ by doing it myself istead of a shop. Plus I like building stuff

[Protephile]

3" is way too big if you're gonna stay N/A. No larger than 2.25 IMO.

[sasp5]

3" is way too big if you're gonna stay N/A. No larger than 2.25 IMO.

if you have the resources DIY (thumb) 2.25-2.5 is the way to go.

[cheapmiata1600]

Stick to 2.25 and don't be expecting more than about 4 hp.

[Lord_Zath]

2.25 or 2.5 will be fine.

You may also want to weld in a resonator so that it'll help deaden the droning.

While you're at it, why not weld yourself a new midpipe w/a hi-flow cat in it to replace the 2nd cat? That part is very restrictive...

[GNO]

You can also order prebent tubing. Make sure it's mandrel bent.

[i12drivemyMP5]

You could save yourself some time by getting no name stainless mandrel bent catback from ebay then get the muffler you really want & focus on making the matching midpipe w/hi flow cat. Don't forget the header & non-fouler CEL fix. Decisions, decisions, decisions.