Well a friend of my owns a Civic Si coupe and he will be putting a GSR ecu in it or computer as he calls it, and I was wondering if there are any Pros and Cons to what my friend is gonna do. My .02 cents says that his engine will eat up more gas than normal?

 

yea different fuel curve, redline....ect ect

 

So are there any disadvantages to this cause im planing to do it to my hatch as well?

 

There are a number of disadvantages to putting a GSR ECU in a vehicle with a different engine. #1-you will get a check engine light for the intake manifold butterfly valve that the GSR has and you don't. #2-VTEC engagement point will be wrong for your engine, you will probably lose power. #3-fuel and ignition curves will be wrong for your engine, again you may lose power and/or your fuel mileage will suffer. #4-you will get a check engine light for the knock sensor that you don't have. Get a Hondata and have it tuned or at least get a chipped ecu that will be more closely matched to your setup. Kenji on this board chips ECU's.