Can anyone direct me towards a site or manufacturer that produces chips that significantly increase the horsepower of ma TT ?

Tuning, anything, tell me it all folks.

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Alright, so I'm guessing either one of these is my best bet:
GIAC, APR, Unitronics, REVO, and Nuespeed.

Which tune gives me the most ooomph ?

Just go with one that is available at a local shop close to you. The differences between them are minimal. But in general APR is a little more conservative, it has been around the longest and poses the fewest quirks because it doesn't push the envelope. REVO, GIAC, and Unitronics will gain a little more because they push the tune a little more.