I never said they were different.
the motor internals are the same, that's not the issue for me.
The greytop ecu is de-tuned to a lower hp than the redtop, that's my first issue.
for a discussion about how to bring the greytop up to the redtop's specs
heremy issues are the ecu, the harness, and the lack of the lsd tranny.
I bought a Celica 98 Redtop w/lsd tranny for $1654 shipped, I think I got a good deal, it just took patience to find it.
With the grey you need a tranny/flywheel, a lot more harness to rewire (the celica red is 99% plug and play), and to get it to be as fast as a red it's gonna take some type of piggyback or full for the ecu.
doing something different is ok if you know 100% what you're doing. Having the time, patience, and money is not easy for people to come by with a different motor swap.
now back on topic, if the grey top was a good deal (first thing I asked), you have a tranny, you're a wiring guy so you can do the harness yourself, and have the means to get the potential out of the motor (at least up to red's specs), then be different. If I had those things, I would.