Originally Posted by slovak
Actually, the 43 dose have boost creep issues so that's why you need to get them ported out, found that out the hard way, but it did not cost me much thanks to my shop.
Yeah if its an IHI you can count on a good chance it will creep on the 2.5. They are just not quite as good of a design as the mitsu based turbos. Even then, the mitsu turbos can creep. I am of the opinion that creep isnt as much an issue caused by that, but caused by the hot side being too small for the engine itself. Here is why I say this.
-From what I have seen, TD06s creep less than TD05s
-8CM housings creep less than 7cm. Most 8cms dont creep. It seems like maybe not most 7cms, but a lot, do creep. You definately stand FAR less chance it will creep on an 8cm housing than a 7cm.
-2.0L wrx motors dont have anywhere near the instances of creep.<which points at the turbo being more properly matched.
-the way a 16G "feels" on a 2.0L, is the way an 18G "feels" on a 2.5L This is a compressor difference obviously, but as far as "this is what it feels like it should have come with", that is a decent comparison. That tells me that they are more properly matched to those motors.
People also need to understand that porting the turbo doesnt only benefit you by reducing creep. It wildly changes the spool and response characteristics of the turbo. This isnt as much of an issue on the 2.5L as it is on the 2.0L, which needs all the help it can get in that dept, but its still a big difference between how fast a ported turbo is than a non ported turbo. Moral of the story there is that ANY stock location turbo benefits from porting. Even a TD06-20G 8cm, will perform a good bit better if properly ported.