Jebus Cristus... PUNCTUATION and SPELLING, PLEASE! That's "apart", "Cometic" (note the capital, the misspelling is understandable), and " 'cause" or "because".... Hi, I'm CRE; Grammar Nazi and general dick. The Comma (,) is right next to the letter M; Just next to the Comma is the Period (.).
If it's a N/A head you'd be well advised to replace the intake cam with a GTE cam; The exhaust cams are the same. You should also inspect the cams and check the valve/shim clearances:
http://www.cygnusx1.net/Supra/Librar...aspx?S=EM&P=48
http://www.cygnusx1.net/Supra/Librar....aspx?S=EM&P=9
The valve/shim clearance is one of those things which most DIYers take for granted that can have a major impact on the efficiency of the engine.
EDIT: Here's a link to an online version of the Toyota Service and Repair Manual for the '91 Supra:
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/ Most of it is accurate for all MKIII years; The wiring varies a bit between years.