Race cars in
AO Silver Member
Join Date: Oct 2007
Location: South Africa
Expansion is better than reducing in the boost pipes - no step is ideal.
For instance if the turbo outlet is 50mm - keep the pipe to the intercooler 50mm. If the id of the throttle body is 63mm, make outlet of the intercooler 63mm and keep the pipe 63mm to the throttle
That said, you'll loose say 0.75% by reducing the pipe and the gains in the better intercooler is say 5% - so you still win