The resonator flange bolts might not break if you can use a torch to heat the flange. In my experience, one will snap off. You can drill that out and use a bolt and nut, no worries. The front ones might back out a stud but thats OK. If you buy a zzp DP, they can come with proper gaskets depending what you order. I have their 2.5" dp on my 99 GTP with no complaints but use a rear 02 emulator. I got mine so I'd have a new flex joint, cat, and u-bend delete all in one. The only thing to swap over is the O2 sensor.
