It's a space issue. That's like comparing putting a dining room table in your backyard or your bathroom.
ill be damned if i find mufflers that sound better than stock.
She's getting a Chris Alston triangulated 4-link rear and front subframe, all C5 stuff up front. QA1's, del-a-lum bushings LS6 cam+intake/patriot heads 5.3 truck motor to a TCI 6x tranny with the paddles. It'll be a runner. Doing 1.75-2" stepped primaries out to an X and dumps. Good thing it's a father-son thing. No way I could bankroll that alone haha.
I haven't done it to my GP... I did it to my silverado. I had 3" duals with glass packs done on it for $300. So i assume that 2"-2.5" won't be much more.
Back on topic, It is rarely worth it to reinvent the wheel. This platform is 15 years old now. Very little is left in uncharted territory.