do the head swap first. the 96-98 heads are crap! they will choke the blower down. it's like 10lbs of chit in a 5lb bag. most guys are gaining anywhere between 45-60rwhp from the head swap. you can still boost your motor but make sure you get a real good dyno tune, keep the boost down(don't get greedy), and use a intercooler, preferably.jmho. one guy on the net is running a 10lb vortech on a headswap car and is making 454hp & 457tq at the rear wheels
i pesonally would rather run between 6-8lbs on 10-1 compression but thats jmo. good luck.
leon
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96 stang,ported 99 heads, 99 intake, 99 cams,Steeda power pullies,Kirban adj.reg.,Pro-m 87,24#inj.,70mm t/b,BBK longtube headers,Bassani x-pipe w/cats, Dynomax ultraflow catback,iat mod, home depot ram air, k@n,373's,cobra brakes,fms spings, tri-ax shifter.
best et 13.80
best mph 103.3
bfg street tires,bakersfield, ca