hey i did same thing to my VS about 3 months ago, and the car should not even crank if that wire isnt shorted, if you have the correct computer for your gearbox and motor combo it is simple.
its there are heaps of threds on here with diagrams on how to wire the speedo sensor ect.... remember also if your car has cruis control put a sensor on the clutch so when you change gear it dont flare the engine.
make sure your O2 sensors from both cars are same some are 2 wires some 4, could cause isues. also if using the T5 gearbox the speedo wire needs to be moved on the ECU im not sure if this is the same for the Getrag.
when compleeted my car took ages to get fired the first time probably coz the fule had drained all the way back to the tank leving big air pockets in the fule line. also im running the auto ECU and i dont think it liked that lol. but even on the auto ecu im getting better fule econemy over 500ks per tank running vortex 98(on auto i was lucky to get 400 at best), and now quite easy to get it sideways aswell
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after doing this my car with 300,000ks on it was able to hold its own against a VZ V8 SS ute i lost of corse, but my m8 was embarresed to have my old banger only a car lengh behind him at half way on the 1/4 mile after that it wasnt rely a race anymore lol
not bad for a v6 tho.
1 Commodore $2000
manual gearbox converson with new clutch kit $1150
Limited Slip Diff $400
The smile on My face the first day it rained, PRICELESS
pics for wiring here