JDL UQFP mated to Invidia Q300 help
 

Hey everyone just installed my new Q300 and I am having and issue mating it to my JDL UQFP.

I have a massive exhaust leak right at that junction. I assumed it used a flat gasket and installed it with one. Wrenched it down as tight as I could with no results. However, looking at it a second time, is it actually supposed to use the OEM donut gasket/spring bolts?

I bought the JDL used so don't know what that one is supposed to use. But it has flat flange end so looks like a flat gasket is the correct one for that side.
Although, after looking closer at the Q300 mid pipe it looks like it could possibly need a donut gasket.

I thought I posted this in the "Issues" section. If a mod wants to move it to that section.

What exactly are you asking? The JDL UQFP is available with a flange to suit some cat backs or with a donut gasket setup similar to OEM to suit other cat backs. It sounds like you have the wrong combination of the two.

lol I'm not so good with words. I guess my question is does the Q300 use a Donut gasket?

The JDL pipe I have is for a flat gasket set-up. I used it with my Corsa so I know that at least.

If the Q300 DOES use a donut gasket, is there anyway to mate the two? With and adapter possibly?

Yes, the q300 uses the donut style.

I'm not aware of an adapter but I'm sure one probably exists. I think worst case scenario, take it to a muffler shop and they can either make you an adapter or modify one of the pieces to work with the other. Won't be pretty, but it's under the car so looks aren't important. Would kill resale on the modified piece, however.

Thanks guys! That's what I needed to know! If anybody knows of said adapter, as I really don't want to have to weld something onto the Q300.

I had this same issue on my 02 wrx. I just cut off the doughnut flange and welded on a flat one.

I just did a quick google search for "donut to flat exhaust adapter" and quite a few options pop up. You'll have to find the right one for your piping diameters. Looks like what you need is out there.

I tried a similar search string, but only found 2.5"-3" donut to flat adapter. I'll try your search string. Thanks for the help!

You could always have a 'v-band' welded on. At least that way, the exhaust wont be one piece.

Worst case scenario, you can find a shop to weld on a flat flange for under $100. I had a shop change my stock catback to flat flange for $80.

I just wanted to mention that I also have a JDL setup up front mated to the Q300 catback, and I also had the leak problem. I solved it for a while myself by using both a donut and a flat gasket. But then it started again. So I took it to a proper exhaust shop who used some nifty flange & clamp parts that they installed for $40 that solved the problem, seemingly for good. We shall see.

Unfortunately, I have a new problem which is that the Q300 is a lousy system. All the supposedly advanced damping material is burned off after a year of driving and it sounds horrible now. This is going to be the subject of a new thread. I'm ultimately looking for a new catback system now, leaning toward Corsa.