2006 R-52 JCW 210hp car. Cat-back system is fine. No rust FL car.
I'm tired of looking at, and clearing, the CEL P0420 code. Mat at Mintech thinks the cat may be plugged. So I'm shopping. NAM has so much info on exhaust i am suffering paralysis by analysis. I am always looking for power gains and a little more de-cel pop is always welcome but nobody likes drone. Front runners are Milltek and JCW of course, put back what's there already with the JCW stuff? (why so cheap on ebay?) Milltek or one of the 4-2-1 headers on the market. One thing I do not want is a CEL problem. Adrian says not to touch my factory tune. So are all the bugs out of the Milltek now? Bolt on and go? Stick with JCW?
What say you?

 

I'll be monitoring responses but one question is whether you intend to retain usage of OEM (or aftermarket) resonator? Unsure of brand of headers and hi-flow cat on mine installed as part of 2006 performance mods, however as described and shown in my (sig) topic, that combo puts the cat flange at such a position which provides inadequate clearance at the res can leading edge to bottom of tunnel and adjacent shifter box. When outside and garage temps warm up later this week, I'll be switching back to Milltek non-res pipe to avoid direct contact with resulting resonant frequency transmission into the cab. Point being, you'd likely avoid that possible issue with an OEM header/cat...

 

Thank you. One point should be that I dont have to install the cat. FL. doesn't inspect. The car is my daughter's school rig daily driver but we make Dragon pilgrimages, x cross and she basically drives it like its stolen. Pros cons of cat and res delete?

 

My non-metro location within Arizona doesn't require inspection either, however does where the original owner lives at eastern suburbs of greater Phoenix. Regardless, I'd prefer to keep it in legal compliance within my own state. Let's not even get started on Calif compliance! Thankfully, this former SoCal Baby Boomer refugee got out of there!

I will note that combo of aftermarket header/cat plus pulleys and other engine mods (still TBD) makes my car a bit louder than otherwise. If combined with no cat at all, louder yet. My plan is to install add'l sound deadening heat shield material already on hand under the OEM tunnel shielding with objective of reducing dBA inside the cab while somewhat louder out the exhaust tips without the resonator in play.

 

Yet another header into the discussion: RMW header with GESI cat. Performance without throwing a code. The GESI cat will support up to something like 450 hp. Fits to the cat-back exhaust perfectly. Pricey but have been very pleased with the quality of workmanship and performance. (Please, no side-bar disparaging remarks about RMW). As for cat and resonator delete, the noise level will be extremely high and you'll get more, snap, crackle and pop than a 55 gal drum of Rice Crispies.

 

Hi NC, when you say it fits cat-back perfectly, does this include the OEM 2 ball cat back, not just the JCWs? Also, your sig says Milltek, I assume you have experience with both Milltek and RMW headers, which one do you think produces more power? - my bad, I just read it again, you have the V2 header.

 

R53, I've never had a MILLTEK header so I can't compare. From an engineering and quality aspect, surely the RMW will have an edge. We know from previous experiences we've read here on the Forum, some have thrown codes with the MILLTEK. As for stock, JCW or MILLTEK, all cat-back exhausts should be the same distance from the flange.

 

I still don't know what brand header/cat was installed on mine nearly 16 yrs ago, however no codes seemingly ever resulted. Seems similar to Milltek's (image below snagged from WMW's online catalog) but unsure if they even produced that item back then. Your statement is true by fabrication design objectives but IMO incomplete WRT other factors common with aftermarket performance parts not produced on OEM type jigs. By that I mean, the cat flange position is more consistently controllable than angles resulting from the total weldment including the flex pipe. On mine, flange mating position is fine but clearance above is marginal. Flange position has some fore/aft tolerance considering hanger rods, rubber hangers and slip-pipe behind whereas clearance to the chassis above does not. Pics show both Milltek resonator pipe and non-resonator pipe versions as installed from opposite sides, each using OEM hanger plate bolts snugged flush to the chassis. With the res-pipe version, insufficient clearance at the leading edge for ~ 5" diameter res can (even after using longer bolts with nylon spacers in an unsuccessful attempt to maximize clearances) whereas no clearance problem at that location for just the 2.5" OD tubing.

 

Well the stock header and the JCW are the same part, there isn't a JCW version of the header manifold.

So if you want to gain some more power you need longer primary tubes so I would go with the Milltek as it will be a bolt on and the cat section can be removed to change out if you want to go cat less or use a different cat. I've used and installed many of these.
https://www.waymotorworks.com/millte...fold-pipe.html

FYI the picture on the website is the older pic as it doesn't show the new version with a flange in front and behind the cat to swap it out, but all the new ones have it removable.

 

That looks like what we are going to do. The thing keeps throwing CE codes for a plugged cat.
So what's the discount code again?

 

Most excellent turn-of-phrase there!

Well done, and it accurately describes the cacophony of annoying snap-crackle-pops from a de-catted non-res exhaust! LOL

Although,
I won't disparage it too much since some people do actually like it.

 

Please clarify, i.e., is your Milltek resonator (or other exhaust component) making "direct contact"? If so, where? The problem I posted in January turned out not to be related to the 4-1 header with hi-flow cat flange position but instead, the B&M SSK extended box which was installed as part of performance mods when my car was new. As such, no room for roughly 5" diameter Milltek (or similar) resonator can there.

IMO, combo of stated header with non-resonated cat-back is too loud - at least for me. I ended up adding a Vibrant 4" x 18" OAL Bottle Resonator in the mid-pipe (pics in my sig topic) which helped a lot. I have a 2nd of same size ready to install in the Milltek non-res-pipe as soon as I confirm sufficient clearance to avoid contact with the shifter box (need 5/8-3/4" minimum beyond diameter of Milltek 2.5" pipe). As is now, sounds good around town and at level highway speeds but still too loud on local mountain grades.

 

I think he’s referring to the bottom of the pipe making contact with the exhaust hanger plate. This happened with mine and I ended up splitting the bracket in two, removing enough material from the middle that the pipe doesn’t have any portion of the bracket under it. Doesn’t seem to be a problem. I have a spare bracket in case I want to try hammering out a concavity on it to clear the pipe.

I’m not sure about the spacers though bc those hangers have a little portion that tucks into a small opening in the bracket. That part of the hanger wouldn’t fit in that little opening if there are spacers between the hanger and the bracket, but maybe that’s okay. But then I guess you’d need spacers for all the bolts that connect to the body as well.