I own a 2006 srt design and from everything ive read and learned myself, is that they're basically an srt8 without the engine upgrade. And possibly a stock cold air intake, mine draws air from behind the drivers side fog light basically. But thats about all ive come up with. So i have srt8 seats in mine, 20" srt rims, the front bumper is the same as the srt8 and i have the small srt8 spoiler on the trunk. I've also seen some specs that say they have like 8 more hp but i cant confirm that. Ive even tried to find production #'s for the srt design but no luck so far. No matter though, cause i love my 300c srt design lol favorite car ive ever owned.