I've had the 2.5" Pypes X-pipe system on my Duster since 2009. Considering I used round canister-style (like a glasspack) Classic Chambered PowerStick mufflers instead of center-in, offset-out oval-case mufflers like the system is intended for the fit was great. Still holding up excellent all these years later although I have to admit I'm kind of tired of the X-pipe sound. Very little corrosion present, at worst a tiny bit of discoloration but I wouldn't even call it surface rust and that's after tens of thousands of miles of street driving including in rain and occasionally even in snow. I have some Doug's long tubes sitting in a box waiting to go in the car (currently has Hedman Tight Tubes) and when those get installed I'm going to run 3" pipe off the header collectors all the way to the 2.5" mufflers; if I do add a crossover it'll be an H. My general conclusion and opinion (verified by an Engine Masters episode) is there isn't much performance difference between no crossover, H- and X-pipe on a traditional 90-degree cross-plane-crank V8 until you get to really high-RPM stuff and even then it's combo-specific, might make a small difference in power might not. I know all modern (since the 2000s) V8 cars use X-pipes but I think it's for noise, it makes the exhaust noticeably smoother and lower volume. I want the old-school deep THUMP THUMP sound from my car, X-pipe has more of a "scream" IMO.
