The motor should easily handle a 175 shot. Just be conservative on the timing, and keep a close eye on the plugs. Maybe spray in just 3rd gear, then immidiately pull a plug.
As far as gear goes, it depends on how fast you are running. I imagine you are going mid-low 12's @ 110 on motor, and 120 plus mph on the hose?
On 3.73's and a 26" tall street tire I was past my 5500 rpm shiftlight trapping 123 mph. I had to go to a 28" tall tire to keep from running out of motor at the end of the track.
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1988 Mustang GT
11.8 @ 123 (7/14/01)
11.5 @ 120 (9/14/01)
1992 BadAzz Wrangler
1993 Explorer
See my car at:
www.mustangworks.com/cgi-bin/moi-display.cgi?179