I came about my 2009 Evo recently, and fixed her up nicely. I tried searching for the above mentioned 65mm TB, but its discontinued. Chat GPT isnt as smart as its claimed be, and mentions the replacement PN is MN137955, I found it to be 63mm, There are a few other pns I found browsing the net, but 1450A036 seems to be the closest to the correct TB. Comes from a 3.8 Endeaver, and also fits a 3.8 Galant.

Am I on the right pg, or am I just tossin money away on the wrong parts?

 

The MN137955 unit being ~63mm is correct, and that’s why it feels “wrong” if you were expecting a true 65mm setup. Mitsubishi often rounded marketing specs or changed casting revisions over time, so the advertised size doesn’t always match the real bore.

The 1450A036 from the 3.8 V6 models is closer in behavior, but it’s still not a direct Evo plug-and-play upgrade. Even if it physically fits, the ECU scaling, airflow characteristics, and idle control can differ enough to make tuning messy.