Heres a look at my intercooler that I run. It's a HKS core with the piping system that came with it. It was supposed to be a bolt on kit but, I bought it used like many other parts on the car and it didn't come with instructions. When I talked to the person that I bought it from he told me how to plumb all the pipes and some were supposed to go under the radiator support. I didn't like that idea much and thought I would cut some of it up and make it to my own spec's. I bought a cheap belt sander from a discount store for 30 bucks to use to help get the pipes ready to be welded. Then I used a Saws-All to cut the pipes. After that I duct taped the pipes together and had them welded together at a local muffler shop. It all turned out good and I've been very happy with the results from this setup as opposed to the other setup that I had cobbled together with different pipes and several silicone couplers. The old setup looked OK but, it often leaked and at the time I didn't know it but, it caused several psi of restriction in the intake path. After the new setup was installed I had to up the fuel pressure and lower the boost level. The next time at the track I ran almost 4 MPH more in the 1/4 mile. That equals close to a 40 HP increase with just a change in intercooler and pipes. Theres nothing wrong with using Junk Yard stuff but, you really need to try and make the pipes as smooth as possible. As you can see it does make a difference when comparing an OEM intercooler and one from the aftermarket.
I have also made a air deflector to force the incoming air into the intercooler instead of letting it flow around the core and find the easist way to make it out of the car. I still need to finish the other side of it and take some pictures so I can show you what I've done to help it out. I haven't done any test to see how well it works but, I have read that using defelectors can make a huge differnce vs not using anything to force the air to go though the core.