Great post!
I've also done a set of mod stock 08 exhaust with good results. I'll try & post pics soon...till then a description will have to do..it's a complete system, header & mufflers, gained a 4hp to 5hp improvement (dynoed)(182.4) & 15 lb weight reduction, while keeping stock appearance. It did take about 8 tedious hrs to do,(with help from a local racing pipe builder) I've decided to go full race,(prepping for the Texas Mile),so i'm considering selling this system, will post in the classifieds.
I cored the catalist out of the stock header,(alot of work working thru the rear)(almost indestructable material)!
Then removed the small spot welds from the rear muffler caps,unscrewed them,trimed off the rear can lip,(folded over) & completely removed the stainless canisters,from inside cans(no longer used)...rolled a peforated core,(sized for the inlet of mid-pipe & outlet of cap (slight increase in diamenter,slightly tapered meg)(had it nickled plated),reassembled with packing (stainless & fiberglass) to fill the canisters,reinstall the rear cap screws(w/nuts),reinstalled the rear caps w/small stainless rivets to the cans.
No one have ever noticed that there not stock!...not even the tech inspectors....they do have a nice mellow sound,deeper & slightly louder than stock.
I'm new to this site and was curious as to whether anyone would be interested in this system.