I ordered a HMS cat-back system a month ago that was supposed to be delivered in two weeks. John e-mailed tonight saying that it will not be ready for another couple of weeks. He said he has the Corsa system in stock but I like the look of the HMS system better. I think I may just ask for a refund and go with another tuner. HMS claims around 25rwhp with the cat-back system. Does anyone have any suggestions? Also, I looked at TNT's system but from the pic it just looks like some mandrel bent tubing with tips on the end. No muffler? For 2000 bucks. I know we own vipers but my god is there really that much of a difference between the $400 systems that are sold for mustang cobras and the $2000+ systems that every tuner is selling? What system has the greatest gains? How hard is it to install headers? Do it yourself job or pay viper tech buttload of money job. Any input would be great.