I have messed around w/ a friends' SRT8 300c, pre-headers its was neck and neck w/ me inching him out at higher speeds. Now just ran w/ headers and it was a couple/few lengths for sure. The headers help immensely at speeds over 60/70mph IMO.
Heavier car + inferior tranny pretty much balances out the power advantage
'08 GT sport/premium, tints 20/35, 18" TSW nogaros w/ bridgestone blizzak winter, 19" sport oem w/ hankook evo summer, Philips crystalvision bulbs, debadged, Vararam OTR, JBA 1-3/4" LT's, ported TB, MF axlebacks, MF X-pipe, DBA-powerslot brakes, russel SS lines, hawk ceramic pads, GXP shocks/struts, lovells poly strut mounts, Slowhawk Tuned 344/356
Gone -'04 GTO A4 2.5" custom exhaust, sweet thunder muffs, H pipe, Z06 heads, Baer brake it, 20% tints, torrid red, AEM brute force intake, tuned