You won't see any significant increases by adding anything short of an SC to your X5. Since I have owned my X5 I have added the Dinan SW, TB, CAI, and exhaust. I think all 4 of those items work very well together. Granted I didn't see a great HP or Torque gain, but it does transform the X5 into sounding and feeling more aggressive.
I am sure some of the other X5 owners that have some Dinan mods will say that probably the best mod is the Dinan SW.
