Thats odd, I would figure that the 98 NPI cars would have an even lower RPM due to it making even less HP up there. 05s also have a 6K redline...heck even the 01 bullitt stangs have a 6K redline. I shift at 5800RPMs right now, after cams if all goes will ill up it to 6250. From what I hear the limiter is the same on all the cars 6250 and ford suppodely gets a test car and bounces it off the limiter for 30 mins straight. If it doesnt let go then it passes. If the limiter is set at the same RPM I wouldnt worry about it, the internals of all the motors are about the same strenght, the 05 being the weakest. Its funny, its the 05 guys that are shoving S/Cs on their cars and dynoing them at 450RWHP and 6700RPM and no breakage. I dont think our motors will last 6700RPM on a dyno for 1 pull LOL, but i guess they will.