ok heres the situation my cuz has a 2000 si with a gsr swap, (keep in mind we didnt do the swap ourselves car came this way) now i drove the car and it felt no where near a gsr more like a LS all i feel is the tq and no hp.

first thing i suspected is the ecu so i went to check and its a p2t si ecu, i believe this is the problem but im not 100% sure before we go out and purchase a p72 gsr ecu.

another thing we were thinking about using a obd2-obd1 conversion harness and a obd1 gsr ecu how much would that actually help.

 

yup daz the problem. that ECU does not open the secondary butterflys in the GSR IM so making revving above 5500 useless. so get GSR ecu and have a hay day!

 

untill then disconect the vacume line to the butterflies on the left sid eof the manifold. THis will leave them open all the time. It wil hurt bottom end power a little but the top end will be much better. I normally leave mine disconnected when I race. It seems to help when on the bottle.