Just wondering what are the difference between a s4 and s5 turbo. And if the turbos are the same in the u.s. and in japan for the given years.

 

Turbo's are the same from US to Japan.

The main difference is the hotside of the turbo.

The manifolds are S4 or S5 specific

So if you have an S5 you need an S5 manifold.

S4's have a twin scroll system to try and quicken spool.
S5's ditched this and added a second wastgate hole to help alleviate boost creep.

 

Remove the word "try" and you're correct.

This is wrong. There was no boost creep with the S4 wastegate, it holds boost just fine until you start messing with the car. The dual-port wastegate was simply an extension of the fully divided manifold design, keeping the two exhaust passages completely separated for as far as possible. The fact that it can flow much more than the S4's wastegate is just a bonus for modifiers, not a design goal.

 

how can i tell the difference by looking at the turbo?? sorry im a newbie

 

If the turbo's off the car the wastegate is the easiest thing to check. S4 has one port covered by a small round flap; S5 has two ports covered by a large oval flap. Externally, the S5's exhaust housing has a large bulge on the bottom for one of the wastegate passages.