I am aware of the head issues. Yes the transmission is better and a few other kinks are worked out vs the 06 or 07.I debated on a c5z and c6z. Went with the c6 and don't regret it. Amazing machine, and they can be had pretty reasonable these days. However make sure the one you get has th heads fixed, or have them fixed soon after purchase. The ls7 had a valve guide issue among all years. Some dropped a valve at 15k miles, while others were at 100k without issue. What makes you want an 08 over an 06/07? The tr-6060?
Here is mine. 520whp with slightly milled heads and a torquer cam. Stock manifolds with a zr1 x-pipe to modded stock mufflers. And it will pull a lot of higher hp cars, including a new (stock) z06.
Is yours really loud? I do not want loud or any drone.