you don't need a different tranny to get the car to top out around 180 or so... just a different rear end. Not sure of the exact ratio but some of the big power boys run 2.8x iirc.
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1995 BMW 540/6 - The Track Rat
2009 Ford Escape - Stock Toy Hauler/DD
2007 Lexus RX350 - Stock Wife Hauler
2009 Kosmic - The Toy - 125cc Vortex Super Rok TAG, (For Sale - $2800)
2007 Intrepid Silverstone - The Faster Toy - CR125 6-Speed