Does anyone know if the 90mm (4-bolt) J-Tube has a physically larger tube allowing more CFM to the supercharger than the standard 78mm (3-bolt) tube? I have a 4-bolt flange welded onto the original tube. I am just wondering if there is more to be had with the actual 4-bolt tube.

 

Same tube, different flange for the 90mm TB.

EDIT: I stand corrected. Eyeballing it a couple of years ago and it looked the same tube to me, but I didn't do a side by side comparison. I would trust the guys below more than my opinion.

 

I'm pretty sure the whole tube is larger... I remember seeing pictures from a couple years ago when Roger made the change.

 

I remember the tube itself being larger.

 

I don't think the tube is any different other then at the flange area. I have one that I would be willing to measure with some calipers if you can post up a pic showing me where you're measuring yours if that makes sense. Let me know.

 

I contacted Magnacharger about the 3 vs 4-bolt and here is their response:

"The newer elbow for the MP122 and later model GM trucks with a MP112, is still the same elbow, the front flange was the only change that was made."