Not intending to add another thread regarding purchasing/replacing a manifold with cat... BUT - I too am in need of replacing mine in my 04 R53.
I was shopping around the Web and came across listings on eBay for new, stock r53 manifolds with cats for significantly less than what I expected to pay for an entire (stainless) assembly, e.g: manifold to cat for under $300.
Just wanted to hear your thoughts with respect to these manifolds listed on eBay.
Is there something more I should be aware of? (price/quality = "you get what you pay for"?).
Or better yet; If you were on a budget would you trust to put one of these (eBay manifolds), in your Mini?l

I appreciate your input.

 

@Here2Go While i have no experience with R53 ebay cats i did play this game with Subarus!

They are 100% you get what you pay for, that being said they will work for a short time. The metal quality is often questionable and very thin, but the main problem is the cats themselves are made cheap and fail leaving you back in with 02 issue (from my experience within a year). The subaru didnt care much when the cats failed and went into permanent rich fuel trim to "save" the engine, i assume the mini would do the same and it would drive like a loaded train. You also need to look out for wording on some of these ebay ads, some are Stainless Cats while the tubing has only been coated in stainless looking paint. The subaru ebay cat was equally price enticing at 300ish while the OEM dealer was 2000+.

Personally would install a used OEM header which is functioning fine over an ebay one. Even a solid manufacturer like magnaflow would be better then ebay and cheaper then oem.

Best of luck deciding!

 

i'd use it as an excuse to get something good. you want something that will last and not be too noisy on your trips. but obviously one must work within their budget

 

Those are perfect for someone who just needs to pass inspection. I suspect you'd start to throw codes a few months in...

 

Thank you.
All replies were my thoughts exactly. I just had to ask.
I will source other options including just having a new CAT welded on to my existing manifold.

Speaking of which - Since having returned from Amarillo on a short trip, I have noticed that my max boost has gone up from 13psi to 16 or 17psi @5k rpms ever since this exhaust rattle/CAT failure occurred.

I've been up here at higher 5k elevation for several months now and had seen my -hg climb fom -18 to -14 with reduce boost maxing out @ +13psi.
Perhaps there is a coorelation between the 2wo?
(more unrestricted flow from the defunct CAT?)
However, I've yet to get a CEL or any codes as of now.

 

@Here2Go likely a solid correlation between the two, there is often an upper and lower setting of air fuel ratio. What the cat / 02s do is manage that level by reading the 02s, reporting back and adjusting the fuel trim to the proper level. If the cat is underperforming it will certainly dump in more fuel, if the cat is somehow over preforming it would lean out.

I know the subaru would drop about 3L/100km on a failing cat which is about 94 mpg if converted correct. It adds up!

 

If you've got scrapyards in your area, find an R53 (maybe even R52) in the yard from which to pull a stock manifold/cat for pretty cheap, I would imagine.

 

Yeah - That was my first thought too.
Then I remembered back, when I was out in Atlanta hitting all those salvage yards - most of (if not all) CATs were cut out from all of the Mini's before they were put out on the yard.
I know of a few Mini's that just landed one of the yards out here in the SW valley (ABQ). I've been out there several times but honestly never thought to look underneath them. You are right. I might just get lucky.
Thanks.

Btw: Anyone have a Magnaflow CAT installed on their Mini with the stock exhaust?
If so how much louder does it make it?

 

I have a 56k stock S header and cat that I removed to install the rmw header/cat. Is this something people want? I offered it and an extra head I have for sale but no interest.

 

I maybe interested in the header/manifold w/cat.
Wondering where your located? Hopefully not too far.
You can PM me.

 

@Scoobaru2010 Well you certainly know your stuff - I'm beginning to experience everything you described in your previous replies while I continue to drive my Mini with a failing/failed CAT
Whilst/since the internals of the CAT have broken; Although I'm enjoying seeing my boost needle hit 16+ PSI and the obvious audible increase in the Supercharger whine; The downside is, Yes - There is a very noticeable decrease in pick up (no joke! - It really does feel like I'm "driving a loaded train!"), gas mileage has significantly suffered and the Mini is back to running even richer like before I had the @adriancl tune.
Thanks for the heads up!

BTW/ADDENDUM :
I may consider having the CAT replaced with a Magnaflow (if I don't go with a good used OEM complete header replacement ); Question is : IF I do go with a Magnaflow CAT, could the pre-CAT be part of the equation that would need to be replaced as well???
I don't know if mine is bad as well.
Thanks.

 

Suggest you do something soon. If the Cat gets blocked, the car will shut down.

 

Lol many a years trying to defeat subarus cats, they won and i eventually just drove around full rich mode for the awesome sound! So yes your on this line right now as well!

The pre cat apparently has no effect, as taken from elsewhere "You’ll be absolutely fine without the pre-cat, makes no difference to the post cat sensor readings."

Which would seem accurate, but i would assume some sort of 02 reading changes amounting in a bit of a fuel trim change to compensate. Whether you would feel the slight tune change or not is beside me, but people have successfully deleted the entire pre cat apparently without issues.

Happy motoring!

 

I can confirm that the car does not care about not having a pre-cat. The Milltek header does not have a pre-cat and my car has been fine in the 6 weeks or so I have had it on. No check engine light with the high flow cat, no performance issues whatsoever.

 

Thanks for the clarification and all replies.
Yeah - Dispite my "no ecuses" production/work schedule - I agree with you TRACKRAT - I gotta get this thing taken care of.

 

Sorry folks - Now I'm really getting confused/annoyed.
It seems that; according to the magnaflow.com website, my searches balk when trying to source a magnaflow catalytic converter for an '04 Mini Cooper S. Search results claim: "Does Not Fit Your 2004 Mini Cooper S"
However, I'm finding the same CAT listed as "Magnaflow" on eBay that claim to fit my 2004 year & S model yet compatibility, year/model tab ( #38) seems to end at 2005 Mini?.
Besides the fact that I would prefer to buy a genuine Magnaflow CAT direct from their website, Can anyone confirm the exhaust pipe diameter size for a 1s Gen Mini. The listing shows "2.25 id / "2.25 od?
Thanks!

 

I've got this picture of the inside diameter of the outlet of stock catalytic converter (in mm).

 

^^^Thanks!

 

Well - to wrap things up in this discussion; I finally replaced my exhaust manifold complete with CAT.
Nope - I didn't go with any of those listed on eBay.
Since I enjoy traveling and exploring across our great nation in my Mini; I thought it prudent not to replace my failed CAT with a Magnaflow since I'm not sure where I might wind up next. (Eg: a failed emissions test in a state like California would be a real and costly bummer).
I was fortunate to score a low mileage OEM, complete manifold with CAT from a kindred contributor here on NAM. Long distance shipping was painlessly arranged. The manifold and Cat were and arrived in great condition. (I can't thank you enough Brad!). Having never worked on a Mini's exhaust system to this extent - Removal of my 22y/o,118k manifold went fairly well. The toughest part was manuvering the header past the swaybar. Not so easy considering I could only raise my Mini 13" off the ground... working in a Walmart parking lot. Upon extraction of the manifold, I was quite surprised when I shook it, to hear that the internal material in the CAT had not crumbled into bits but had broken loose intact, as one solid cone/mass. Installation of the "new to me" manifold was a bit of a pain trying to line up the header gasket, manifold to the head. I had unfortunately misplaced a M8 stud I had prepared in effort to help hang the gasket and header on one while I align the rest of the bolts. After a back braking 6hr day, I got to fire up the Mini.
It ran so smooth and quiet (like new), it was hard to tell whether it was running or not. No codes, no noise, no exhaust leak!
A few miles test drive tripped the SES. A quick scan revealed a fault with the post cat 02 sensor = heated 02 sensor malfunction. Id thought it most likely that I may have damaged the post cat sensor during the swap. I had a backup post 02, raised the car up just enough to replace the sensor. All is well. No SES, no codes, no running rich.
Ok that's all great. I'm loving the car again. But...
Now the biggest hassle (for anyone who may have gone through this), - Getting rid of the old manifold/CAT!?!!.
I scoured the Internet to find a local recycle yard. I visited at least 5. Not one of them would take my manifold with a CAT. I know I could get money in exchange for the precious metals in the CAT but still no recycler would take it, (Due to the large amount of nafarious thefts that have happened over the last couple of decades), Not even for free! After 2hrs driving from one recycler to the next, I was just about to give up hope and lay that thing on the side of the road. Until I came across a shabby, run down independent, metal collection/recycle business in probably the worst part of the SW valley. The man didn't speak English but his eyes bulged at the sight of the CAT and quickly offered me $50 cash. Yes I could have haggle and gotten more. But quite frankly, I felt he could use the money more than I and I was just happy (on many levels) just to have it out of my car and move on from this whole episode.