When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Do the LS6 intake, then get a TSP Torquer II or an Futral F11 or F13. Those should do the trick. If you're still on your stock rear gear, don't go any bigger.