i would personally do away with the high speed by-pass due to the set up and nature of your car...the spring you are speaking of is adjusted by tension applied thru the use of the number of shims..its a check valve used at high speeds to run off the extra alcohol...
if i were you i would plug it....
also what you using as a fuel pump ?..also what is your barrell valve leadown set on ,also main jet and nozzels...
thanks brian
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "