I just did both a muffler and resonator delete today primarily to save weight for autocrossing / track. H-Pipe was left in place. Definitely loud, but I knew that going in. Less drone than I expected as well.

I had them put a flange on the tailpipe tips as well as on the original SRT-6 muffler in the event that I need to put it back on quickly due to a sound violation during autocross.

 

the engine needs to breathe remove theresonator, put your muffler back on. the muffler is a total a little over 4" discharge, yet has some back pressure if you need more air out remove the cats all of them.
I have with the V8 of course no cats, noresonator, but added 2.5 pipes from engine to 3" from Y on back into stock muffler ,, there are no headers for a V8 in a crossfire so i cleaned out the exhaust manifolds , with tune ,,smaller SC pulley and exhaust i went from 11.87 to 11.49 in the 1/4 mile. Oh it is not that loud as i drive it every day on the street, just a suggestion I would try the exhaust pipes you have now before going bigger jim

 

I care about the weight savings more than anything else. For my autocross class, only catback exhausts are allowed. On top of that, I'm in CA, so all 4 cats need to stay.

Between having all 4 cats and the h-pipe, there should be sufficient scavenging on the exhaust.

The one caveat is that I'm concerned about not passing sound -- it's 92dB at 50ft in my region, so that's why I had a flange added in the event I need to bolt the muffler back on quickly. If I need to cut the noise down permanently, I figure I can always change to a turndown or cc insert.

 

the muffler does not cut the noise that much,, the res is the biggest weight removable, can't see your rims but the stock rims are 26 to 30 lbs ea. the seats are 75 ibs but i guess u already know that good luck, any thing i can do to help let me know ,, i went to complete adjustable rear suspension removed about 10 to 15 lbs ,good luck

 

That's part of the reason (the other reason is that rubber is cheaper as well in the smaller sizes) why I went down to 17s in the front and 18s in the back. 21.6lb front wheels and 22.0lb rear wheels (but I did have to add a spacer to keep the offset close to stock). The rotational weight savings is actually substantially higher. I didn't spring for the lightest wheels out there, but looked for light wheels that were a decent price. They're also mismatched as it was almost impossible to find matching wheels in both 17x7.5 and 18x9, but I made sure that the paint color was the same (and the look actually isn't bad at all).

Between wheels and exhaust, that's about all I can do for weight savings to stay within my autocross class.

Thanks for your input!