I have a Vortech MAF and you only need to change the sampling tube. Interactive Systems Technologies sells them for about $25 plus shipping. When I upgraded to 24# injectors it solved all my wierd timing and knocking problems. My FPR is set at 26 PSI with the vacuum tube unplugged from the FPR and the engine running, base timing at 16*. Since you're running 19# injectors (factory) you'll have to set it higher, probably around 40 PSI.
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86 GT, GT40P heads, Crane 2031, 1.7 RR's, Cobra intake, 65mm TB, 73mm Vortech, 24# injectors, MAC GT40P headers, 2-1/2" BBK H-pipe (w/cats), Flowmasters, 3.55s, Groundpounder subs and lower control arms, 277 RWHP.
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