The RPM and Performer 5.0 both use the same (identical) lower intake. The uppers differ in that the RPM has 1" less runner length and bigger runners (promotes more power 5000+ revs). You might consider some porting on the lower intake, but I wouldn't worry about it if you plan staying on the motor. If you do a new cam, make sure you have springs that can handle higher revs and/or higher lift (that is, buy a kit, or have a custom ground cam done and get springs to match
). Good luck!
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1991 LX Hatch 5.0L