Hi R53 community. I was planning on changing my headers for my 2004 JCW MCS. I heard that the 4-1 headers really strangle the engine (is this true?). I know that the 4-2-1 headers are good for mid range power and torque, and since it's pretty rare that I redline, I was thinking of swapping to it. I need some help one what things to change and what parts I would need. I was thinking Xforce headers with the JCW exhaust system I have would be pretty good. If anyone has any info, it would be great.

 

You have to build a tomcat or test pipe to connect XForce obx suspersprint to factory catback. They are not bolt in on the bottom end.

that’s why mine is still in the box over a year later. But yes, I’d rather. 421 than 41 header. The only other option is scorpion but they are money. Money since you have to buy them with cat in the US.


the factory system is a 4-1 header, only big difference to most 4-1 is the shortness of the runners because of the precat.

 

I read this and similar related topics with interest, yet with owner's objectives often not fully understood. My R53 was highly modded in early 2006 for tracking intentions but not subsequently done by the previous original owner. From all that, it's taken me a few years of gradual taming for practical streets and highway usage. WRT aftermarket headers, mine installed same time as other performance mods were a quality 4-1 fab (actual fabricator not known but clearly not a China or similar knockoff). Pics show some of that but point being, aftermarket headers induce more resonance dBA into the cab than OEM, regardless whether OEM catback or aftermarket (mine currently being fully resonated Milltek). As a subjective reference, my buddy and I did 200 miles mountains roundtrip drive today to Flagstaff in both our R53 (mine returning home with 7.4k total miles and his 2006 Checkmate factory JCW now with prox 8k total miles). Mine runs and handles as as it should with such total mods, however his totally OEM stock (other than with M7 strut plates and OEM cabrio braces) is a far more comfortable and quiet ride. Which one might appeal more to MINI enthusiasts? Each has its own attributes and fan base. Be certain what you wish for as well as your ultimate objectives...

 

Very good insight here with you having driven your highly modified R53 back-to-back with stock R53.

You absolutely nailed it in saying that it is dependent on the owners' objectives for the car and at what cost (financial, time and overall effect on the car) to achieve those objectives.

Please, if you can, elaborate on your point that aftermarket headers induce more resonance dBA than OEM. I too am shopping for headers - leaning toward catted Milltek - for a little more exhaust sound and any increase in performance would be a bonus. I find my resonated Milltek catback system a little too quiet but I really like the tone, so a little more volume would be perfect for me.

**not trying to hijack the thread, just encourage discussion on OP's topic.

 

^^^ I should have written, an aftermarket header in combo with a smaller hi-flow cat (as I believe mine is) produces more dBA by itself than the OEM header/cat combo. Sound is basically resonance frequencies at various RPMs, which then produce associated vibrations of adjacent components on the chassis and interior plastics too - especially noticeable under load such as uphill grades. This pic shows the smaller cat on mine, noting actual manufacturer of this circa 2006 exhaust remains unknown.

 

I'm glad you mentioned the catalytic converter.

I am also considering a header with a test pipe in place of a cat and then welding my stock cat into that. I have emissions testing here in the valley (I'm good for 2 years now though) and I don't know if 1) high flow cats like the ones that come with these headers can pass emissions and 2) how those cats might effect the exhaust sound.

 

this is the exact setup I run, with factory cat welded in (x force 4-2-1-oem cat-JCW)

 

The OP (Kenneth) double-posted a similar question in the JCW Garage forum, so there are additional answers over there:
https://www.northamericanmotoring.co...-2004-jcw.html

 

"As far as 4-1 vs. 4-2-1, the RMW shorty header (with cat) and their race header are widely acknowledged to be among the best performers on a R53 Mini, and both are 4 into 1 designs."
+1! The RMW Shorty V.2 header with GESI cat is excellent and throws no codes.

 

That's what I've read about the RMW header. Does it work well with the Milltek catback? I see you have a tune, I am trying to hold off on a tune until I possibly upgrade to a ported head.

 

If you are thinking about a ported head, or even have a JCW head, You may not want the Milltek. Here's what Eric at Helix in PA, who sells both has previously said:

You may also want to consider that the higher-performance RMW shorty costs $250 less than Milltek, as you can see on Helix's site:
https://store.helix13.com/r53-mini-c...ormance-parts/
.

 

Thanks for that.

I am thinking about the RMW Shorty headers and pairing it with the Milltek exhaust, not the Milltek headers. My only trepidation is that we have the CARB compliant emissions in NY State now.. I may have to replace the cat on the RMW Headers, which would be a lot less fun to deal with.

 

First off, agreed on choosing a header which does not restrict head outlet port profile dimensions, whether that be S or JCW spec or aftermarket ported. Further, choosing a gasket which has adequate relief to those mating ports being essential. OTOH, I've not seen pics on RMW's or Milltek's site nor here on NAM clearly illustrating such mismatching. Web comments on vendor's site or by enthusiast forum members (me included) should be factored but not necessarily accepted as factual.

Lastly, what are your overall performance objectives given your current (sig) mods plus stated emissions compliance regs in your locale plus ease of install without subsequent issues? How much additional gain and is all that worthwhile? As is often said, be careful what you wish for...

 

I am in California, and I have passed the CARB smog check multiple times since new. There is a visual inspection (my underhood looks plausibly stock, with no color anodized or shiny bits). Then they plug into the OBD2 port for readings. Because my Mini "blows clean" (no lights or codes) everybody is happy. I believe both RMW and Milltek are using 49-State approved cats on their street headers.

 

That's the $3,000-5,000 question, right? I just wanted to put on the pulley and do the 100k service on the supercharger, then move on to some cosmetic improvements on the interior.

​​​​But fate had other plans for me, I had to replace the head gasket to get rid of a pesky 0304 misfire code. After I successfully finished THAT (including drilling out a busted bolt from engine block) I felt really confident. My Aisin transmission went out on my first test drive, and now after first replacing the solenoids, then the entire valve body, it's running really well. So I'm thinking maybe I'm not just a hack mechanic after all, maybe go for a stage 2 performance upgrade, something short of a tune. Although I'd love to learn how to tune as well. The whole thing is a learning experience that I get to drive around, eventually take it to the track.

My next build I've been eyeing is an SLC Superlite kit, but I'd need more garage than I have now. Only a Mini works in my mini garage. And I love my Mini :-)

 

That's good to know. Unfortunately, Inside my hood screams Mods, LOL.