I have the Borla duals, sound great, don't think it gained much rwhp. The best upgrade for me has been cam swap. I ran a sidewinder cam for years, finally we did an Inertia spartan plus cam, a more high end cam. My dyno tuner and "hemifever" tuned both cams. I have srt8 valve springs and pushrods. Tuner has it shifting at 6250 rpms now and it really hauls azz. The spartan+ got me 20 more peak rwhp over the old sidewinder. Sidewinder was a bit stronger at lower rpms, more punchy around town. Passing a car at 60 mph with the spartan + is quick. Some ported heads would be nice if you get a nice tax refund, hehe.
Inertia Spartan + cam, Circle D 3,000 stall ,Sonnax line pressure booster, MagHytec 68RE pan,and differential cover, Vararam, JBA's with cut outs, Rancho 9000's, Helwig rear sway bar,3:92's, extra rear leaf,Line-X Bedliner,GY Armortracs, 245,000 miles To Hell and back. 14.2/96 mph NEDW