I have a 2000 hatch with a 99gsr swap.I had my motor sleeved bored to 83mm and it has 9.1 pistons . i was curious if i can use a p72 on my car without messing anything up. I wanna eventualy get hondata but wil this work for now ??? please let me know what to do ...thanks

 

If you're running no turbo on it, you'll still run a little slower due to the compression, but if you're breaking it in, depending upon if you're using stock injectors, it might be possible.

Personally, I'd wait, get the rest of your stuff installed, and THEN break in the motor so it can see boost slowly. If it's a OBD! P72, get your management and get to breaking it in

 

I wouldn't do it... get and EMS to tell the car it has a different motor, with more displacement.
all that money spent on internals will go to waste if you don't get tuned...