Your mechanic is misinforming you, if he's trying to steer you away from the Cobra Jet throttle body. There are zero tuning issues with that throttle body. I have the Super Cobra Jet monoblade on my 2.9 and have never had an issue with it. Before that, I had the Cobra Jet 65mm twin. Never had a problem with that one, either. I've had my Whipple for over 6 years.
I misspoke. I talked with him today and he is RECOMMENDING the SCJ, not the VMP or Whipple (as he's unfamiliar with the Whipple). Thanks for the info, glad to see what others are having success with!