The 08's have a lighter balancer. If you plan to upgrade the blower Ford says you need to change to the 08 balancer on 07's. I have had no problems with my clutch and I have not had the TSB done. I have heard people say that after they had the TSB on the clutch done it was much much better. I am not sure what the TSB is, possible something with the throw out bearing.... maybe a little more research to be done...
I also have a 09 SRT Challenger and it's nice. It is more of a cruiser than a performance car and my Cobra is my fast car. So it's all what you want your car to be I guess. Since you had an 05 you will know what to expect really. I don't think you will notice a huge power gain / faster until you upgrade the pulley and get a CAI on the cobra or change the blower. Either 1/4 mile or road coarse the Cobra can be made to do very well for both. Good luck on the decision man...
Shawn
__________________ Osiris - '07 Shelby GT500 - Black , Sequentials , DDM 5k HID's ,
Bassani race mufflers , JLT cai , 2.6 pulley , MM Sport Box ,BMR rear end, tri-axe w/ hurst stick & ball , Afco HE & IC res tank |