So i've been researching a bit, and i just sold my b5 a4 last week and got a b6 a4. I'm loving it, all the maintenance is up to date, and it's got a few goods. AWE Catback, 380cc injectors, GIAC stage 1 chip, Carbonio intake, k03 hybrid turbo with k04 exhaust, r1 DV and some asthetic mods. Anyways, My friend has a 18.25" wide (27" from inlet tip to outlet tip) x 6.5" tall x 3.5" deep intercooler with 2.5" diameter inlet and outlet that i could pick up for a reasonable price. My question is regarding plumbing though. would 2.5" IC piping suffice for my application, or is it going to be too much diameter causing me to loose pressure, or is the IC too thick? etc.? I understand that I would probably have to trim the front bumper a bit, but that's not a huge issue...any help would be GREATLY appreciated, as i've searched but i'm having some questions.

 

i would suggest for that turbo to have 2.25 on hot side of intercooler(turbo to intercooler) and cold side 2inch. if you plan to upgrade to bigger turbo, then you can increase the pipe diameters.

the reason for taper is because cooler air is denser thus takes less space up. so to keep pressure and velocity up you must taper down.

 

awesome, thanks tofast2belast! that was my main concern. my other worry is that the 3.5" thick core might be a hair too think. I plan on test fitting it or something this weekend, so i'll see. now i'm just trying to figure out what all bends in the intercooler piping i need to order since i'm sort of piecing it together...