Here's the deal, a little while back I put up a WTB post for and uppipe, saying I wasn't picky. Then I did my research, and turned down everyone who offered me one, because I was now... picky. The reason I need a new one (maybe) is because the weld on the bottom flange has developed some pretty serious cracks. Turns out I have a place that I can probably get the weld repaired for more-or-less free. But, here's where the question comes in. The broken pipe is a Helix. I haven't been able to find any numbers on what it's exact inner diameter is, but I'm pretty sure its bigger than stock. I'm running stock headers and turbo and don't plan on changing them any time soon. Also have full 3" TBE. So I've been looking at getting a new flex pipe with the stock ID (TurboXS is what I've had my eye on), with the theory that I would have faster spool up times? I'm currently hitting full boost at 3200rpm. So, the Q: Stick with the Helix, get the free weld, or get something like the TurboXS?
In my experience, the up diameter doesnt really matter. I've gone from stock ones to super bigass ones and the butt dyno shows no changes. However, if you do ported manifold and a good crossover pipe, you'll need a better UP (larger diameter, less bends, aka solid one with one smooth arc or one smooth bend) so you can maximize your gains. Otherwise, just slap that shit back together and be done with it.
Not unless you do the porting of the manifold, install good crossover pipe AND do a matched up pipe....I had that on my car...now in my Wife's car. Not only does that setup spool faster, but it has more power eveywhere and driveability is excellent.
So my free weld... doesn't exist. Think I'll just go with the roommates old STI pipe. SOB gonna charge me 30$ and make me mop the kitchen.