I need some guidance, I have a 2007 V6 mustang (it had a 93 octane preloaded SCT X4 tune, and cold air intake, everything else stock). I wanted to get a muffler delete so I went to Midas and they straight piped muffler back (all they did was remove muffler and add a resonator to reduce backfire sound). After some driving I noticed acceleration issues like it would go past 5,000rpm (redline 6000) and it was slower to get to that rpm range too, in addition the shifts were slower and the speed...

Acceleration and power issues after muffler delete