Anthony Always keep in mind the trick manifold picks are nearly all for LH Drive. Positioning the turbo as close as possible to the manifold is most desirable, as the energy in hot exhaust pulses hitting the exhaust turbine wheel really spins it up. The further away the turbo sits, the less efficient spinning up the wheel becomes.
Samman88 Anthony is partially correct but it is commonly thought that although shorter manifold runners will provide greater energy to the turbine and hence slightly better spool time, these gains are minor compared to the potential for exhaust pulses to reflect back into the cylinder (exhaust reversion) that occurs with short tube manifolds and create poor combustion conditions and increase chamber temps and the likelyhood of a detonation event. These will also have poorer flow. Many stock manifolds will have short tubes (spool time, cost, packaging) but most cars hunting power gains will use longer tube manifolds (greater flow, more top end, less detonation, lower cylinder temps). One of the few cars to run long tube manifolds stock was a turbo mazda that had a 14:1 cr. When they had to sell the car in rhd countries and shorten the manifold runners to package them they had to reduce the cr to 13:1 - such was the effect on cylinder temps!
