First off, before I get flamed- I dont have $ to buy a decent ELTM and don't want to take my chances on an ebay one. Im not trying to make super crazy power.

That being said, right now i have a rev-hard log manifold with 2 1/2 downpipe making exactly 400HP(dynojet) on 14-15lbs ....I just bought a Pfab log top mount manifold from a member on the site last night. Mainly did it because the looks. Bottom mount log manifold make the engine bay look so ugly. Anyways...when I put this one on im gonna go ahead and do a 3' downpipe with a electronic cut out. I'm sure the 3' downpipe will help but anyone out there know about how much it'll help?? Im on AEM and keeping everything the same from my old set up besides the downpipe and cut out. Staying with 93 octane as well. Thanks!

 

should be similar results with maybe a touch more midrange from quicker spool with larger downpipe. just guessing of course.

 

you think even with open downpipe?

 

The more freely your downpipe and exhaust (in your case the cutout) can flow, the less energy loss across the comp. wheel...this setup will definitely help with the spool.