Looking to purchase 05 -10 GT but, leaving a 302 cammed Fox. Cammed 4.6 is a must but, which model. Appears there are FRPP,Comp Thumpr and Brenspeed Detroit. What would the cost be for cams and installation, probably a tune. Any significant difference among those or others not mentioned. Know will never get that Fox 302 sound but, what is close. With an O/R H any suggestions on axle back. Magnaflow or Pype seem interesting.