Well, I'll go into more detail...When I started doing a lot of TB porting, I had a lot of people come back with pegged LT's. On a ported TB, LT's are generally higher than stock, but something wasn't right. Almost every problem was a car with a TB spacer on it. They seal fine when new, but take off the TB, or in some cases, just over time, they warp, and don't seal well. I can't speak for Aluminum spacers (those have been fine over the years), but the "plastic" ones are problematic. Wrapping the crossover, and adding a heat shield would be a better way to go in my book. We even had a local member that had head gasket failure due to hydrolocking the engine at speed...which was traced back to an aging TB spacer that warped, and sucked coolant in.