UEL Header Rasp
 

So I just installed a set of JDL catless UEL headers to pair up with my Spec D (Invidia N1 replica) catback. After the headers were in, I immediately noticed way more rasp than it had with just the catback, it sounded like a tin can full of rocks was thrown into a paint mixer from 3.5-4.5k RPM. Took the silencers out of the mufflers and that helped a lot, but didn't entirely solve it. Stock overpipe and frontpipe. Anyone know the easiest way to get rid of rasp? I want to keep the mufflers if I can, so I was considering having a muffler shop cut the stock midpipe to size and weld a flange on so it'll fit the Y-pipe and mufflers. If I have to get rid of the mufflers too, does anyone know if the Invidia Q300 ones fit on an N1 Y-pipe? Thanks yall.

I believe the q300 has more like a vband clamp right before the actual muffler whereas the N1 has flanges for each muffler then one main one further down that connects to the resonator portion of the exhaust, so I don't think they are interchangeable. However I personally have catless uel headers and OP with a Berk FP with a high flow cat and the Megan v3 catback and it sounds amazing not raspy at all, and the Megan cat back was very nice quality and is also only like 350$ so it's definitely on the cheaper side compared to the q300 or even the N1

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You sure it's not an exhaust leak? tin can full of rocks isn't what I'd describe as rasp

You need a new catback. the n1 (or in your case the spec d) is known to sound raspy paired with a uel header. i had rhe same setup before and sounded like shit

It is possible that I didn't tighten something down right, some of those bolts are hard to get to. It doesn't sound like the noise is coming from the front, but I'll look at it asap. Also no CELs.

I've heard some sound clips of the N1 with JDL UELs and they sound way better than what I got right now (or maybe because all those guys have overpipes and front pipes). Maybe Spec D cheaped out on the resonator badly, but I'll also look for leaks as mentioned above.

Q300 has a slip on joint connecting midpipe to muffler. Regardless Q300 and N1 are not compatible.

After going catless the 3.5-4.5k rpm range on our cars is known to be prone to rasp. Honestly the easier way to get rid of rasp would probably be to get a new catback.

Just do what I did and copper RTV everything!! lol My exhaust leak was driving me crazy.

As far as catbacks go, I was looking into a genuine Invidia system, probably a Q300. I'm gonna try and get the stock midpipe to fit since that resonator is way bigger, a shop should be able to fit it for real cheap. I'd rather not spend $600 on a new catback if I can avoid it.

what @Lakitu said, I used grimmspeed gaskets and high temp rtv on everything even the axleback to midpipe connection, and my leaks ceased. Some of the headers and exhausts may not have mating points that are perfectly decked flat and can cause a leak. Also you won't get a CEL from an exhaust leak if you are tuned or have done a O2 spacer cheat.

Stock tune, no O2 spacers or anything like that. I heard the header gaskets are one time use, I have the Grimmspeed gaskets and the supplied JDL gasket for the header/overpipe flange. If I unbolt the headers to put some RTV, will I need new gaskets?

Side note, JDL says they cut their flanges with a water cutter. When the part arrived, I noticed a slight bit of rust and the flanges were not so smooth. Exhaust leak is starting to sound more like the problem.

I spread mine all around the gasket in a thick bead, I suggest doing this on the grimmspeed ones. Make sure the bolts are torqued down properly when you do this as the rtv should essentially squeeze out. Also don't start the car till the rtv has cured properly if you can, it take an hour or 2 to become "gasket like". I'd make sure you do the header to engine block gaskets as well.

if you want an invidia catback, id suggest R400, or for even lower volume the Q300

Can confirm the r400 is a good exhaust, but they like to break hangers so be aware of that. I switched to a Tanabe Concept G and I like that more betterer.