Perfect Power

Tune your ECU.

This came highly recommended on another list.
Perfect Power (http://www.perfectpower.com/products/smt6.asp)

Lot's of bucks would be my guess.

Also recommended for viewing ECU data was
CarChip (http://www.davisnet.com/drive/products/carchip.asp)

I have (but have not used) this OBDII interface unit:
Harrison (http://www.ghg.net/dharrison/)

Toy Man