Well, there are always a few surprises- Dorman intake plenum
 

As part of the engine (well, it ended up being a total car) rebuild on my son's 2002 GT, I ordered a thermostat. I went to install it in the intake today, and discovered that it would not go into the housing. In fact, it looks a bit different from the thermostat that came out. I had also noticed that the gaskets between the intake and heads were quite different. On his intake, they are all individual O-ring type gaskets, where in the Fel-Pro kit, they are one piece per side. There is no way the Fel-Pro gaskets will work with this intake plenum, as they will not fill the channels the O-rings sit in. Given the differences, I started looking for a part number. I found nothing mentioning Ford or Motorcraft. I did find P/N 615-175 "printed" on the intake. Looking up Dorman 615-175 returns this exact intake.

So now i have a dilemma... What is the quality of the Dorman part? Obviously someone replaced the stock Ford intake on this engine at some point. That goes hand-in-hand with the discovery I made that nearly all the cam bridge retaining bolts were finger tight, allowing the cams to walk, destroying the cam journals and ultimately the entire engine.

Concerns I have are-

Is the Dorman part up to the performance (CFM per RPM) of the original Motorcraft part?

Is the Dorman part a quality piece that will last over time?

I really hate to go out and buy a new Ford intake- especially if he decides to change it later on for a performance part. I guess the junk yard is always an option, but then I don't know what I'm getting.

No, the doorman is a POS. Your best bet is going to be trying to find a PI intake used. Remember that you can use it off from the 01+ Crown Vic, Grand Marquis, and Towncar.

I got my gaskets from autozone, they carry doorman and stock, I believe everyone does. Just make sure you o ring type. And as jc said, the doorman intake is not good