Ok, so my CRT elbow has a 3.5" outlet, and the rest of my piping is 3". Would I potentially see a pressure drop from the sudden change from 3.0 to 3.5" diameter along the way after the intercooler? I'm thinking right about the bend point coming out from under the car is where the switch is going to be made, with a 3.5" pipe running behind the radiator to the TB and 3" everywhere else, including out from the turbo.

Thoughts?

 

Stepping up is usually just fine, especially if it's not right before the MAF.
You can easily make a smooth transision with a piece of 3.5" tubing that's a few inches long. Cut a triangle out of it down its length with a base of 1.5", close up the gap and weld it and you'll have 3" on one side.

 

No maf so I'm not worried about that. I'm just going to do a transition hose at the elbow to get the car going (functionality) then once it's up and running, I'll order some of the 3.5" stuff and make it look better.

 

Aren't you using Aluminum for your cold side? You could maybe use a stainless adapter just to go from the outlet to your cold side?

 

Yeah, just using aluminum. Not worried about using a silicone transition hose at all, those things are plenty good.