09 GC here 5.7...... Stock exhaust is very restrictive..... I put a full srt8 exhaust on and huge difference...... Stock shorty srt8 headers work great....... With a CAI and 93 diablo tune my porky jeep ran 14.18. Not bad for 4400lbs...... Also runs up to 140mph with ease....... Stock eagle heads flow more than 300cfm..... My stock BB edelbrock heads flow 290..... These small block hemis are the shizzle! I plan a 392 rotating assembly and fully ported eagle heads and maybe run the stock 6.4 hemi VVT cam (580/530) lift and right at 11-1 CR should get me around 450 rwhp....... TBF