Owens, the exhaust on the srt8 are close to max on flow, if you want more flow, you have to eliminate the cats and or go with long tube headers. But I don't agree with your local tune shop, the canned tunes do make a difference, all cars are different, some gain more then others. but if you have acces to a good hemi tuner, then you can get some good power gains, a cmr tune is recommended to get the most gains. My 07' srt8 charger gained 28 rwhp with a custom cmr tune. Couldn't tell where exactly the gains were because I did cai, catback n tune all the same day, with just a stock base tune n after mods. Now on My 10' srt8 challenger , I did a baseline, installed mufflers, reso delete, and cai and redynoed and gained 8 rwhp from my baseline run. then after installed canned tune and gained 15 rwhp so up 7 more. Did custom cmr and gained 24 rwhp total. So 16 total rwhp gained from just the tune. All on the same dyne. There have been others that have made more and even less.i've talked to a local tuner shop, by the sounds of it these cars are pretty much maxed at from factory. stock exhaust flows pretty well and not much out of programming. sounds like the camaros and 5.0 mustangs are much more user friendly and they get more power out of them.
Owens, the exhaust on the srt8 are close to max on flow, if you want more flow, you have to eliminate the cats and or go with long tube headers. But I don't agree with your local tune shop, the canned tunes do make a difference, all cars are different, some gain more then others. but if you have acces to a good hemi tuner, then you can get some good power gains, a cmr tune is recommended to get the most gains. My 07' srt8 charger gained 28 rwhp with a custom cmr tune. Couldn't tell where exactly the gains were because I did cai, catback n tune all the same day, with just a stock base tune n after mods. Now on My 10' srt8 challenger , I did a baseline, installed mufflers, reso delete, and cai and redynoed and gained 8 rwhp from my baseline run. then after installed canned tune and gained 15 rwhp so up 7 more. Did custom cmr and gained 24 rwhp total. So 16 total rwhp gained from just the tune. All on the same dyne. There have been others that have made more and even less.