What is does is insulate the TB from the heat of the engine and coolant. I don't run a spacer because I closed off the coolant passages up to that point. It wont give you any more power. What can happen is the TB is cooler and there for may cause a bit less KR in the engine. Perhaps a half a degree to a full degree of KR might get you 1 to 3 hp. Is it worth the cost, I don't think so. But if your looking for every little bit, then install one. Not much to it. Remove the TB, remove the 3 studs, install the new longer studs, gasket, spacer, gasket, TB and your done.
SAVING THE WORLD ONE BONNEVILLE AT A TIME
1997,1998,2000,2005 year confused Bonneville SSExi. Stock? ish.
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