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Discussion Starter #1
I need help determining if I should go full 3" exhaust on my car with the mitsu turbo. 3" isnt much more money and I plan on upgrading my turbo in a year or so but I hear that 3" on a mitsu will cause major boost creep. What are the fixes for boost creep besides porting the wastegate?
I heard that clamping a 2.5" reducer on the end might help?

Any suggestions are greatly appreciated
 

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my opinion is 3" is overkill *unless* you plan two or more of the following

hybrid / larger turbo (S60 or larger, T3/T4, etc)
high boost >20 psi
extensive porting to head, intake & exhaust manis
Much better flowing IC
DOHC
3" swingvalve

otherwise IMO you are adding weight, cost, and complexity for very small if any gains

well it does sound nice too :)

with a Mitsu, to prevent boost creep, you would need to add restriction to the 3" (or 2.5" too) system in the form of a cat &/or muffler &/or other restriction ; I doubt a 2.5" reducer by itself would be enough
 

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Discussion Starter #3
K, Thanks detobias. Anyone think that 2.5" with just a strait-through muffler will still haveboost creep?
 

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I put a full 3 inch exhaust on my van with the stock turbo and I did get a lot of boost creep on my low boost setting. The low setting was the boost nipple from the turbo going directly to the wastegate. Stock exhaust showed about 5 psi, with the 3 inch exhaust it spooled to about 7psi and did the creep to about 10-11psi. Actually I did not mind a little extra boost or the bit of creep, the 5psi was a little too mild for my daily driving habits. On my high boost setting which was 17 psi through a grainger valve I did not see any boost creep. Of course I knew I was going to upgrade to a S60 turbo so when I did my exhaust there was never a question that I would be running 3inch. I hope that my experience will help with your decision.
 
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