I’m thinking about pulling the JCW exhaust off of my R53 and making a custom exhaust for it…..just because I’m bored, and I want to test out my new welder. I’ll keep the JCW exhaust in case I decide to put it back on (if the custom exhaust sound like crap, or it’s just too loud on the highway. I want something a little louder with less back pressure so I can get some more “pop and burble”…..but not annoyingly “ricer” loud.

I have three questions.

1. What’s the best pipe size to use for a cat back system? I think the JCW is 2.25” if I remember right….should I go up to 2.5” or 3”?

2. What’s a good muffler that is small enough to fit up under the back of the car, flows really well, but doesn’t have a ricer sound to it? Magnaflow?

3. Where can I get a new flange that bolts up to the cat? I don’t want to cut the flange off of the JCW system to use it on the new setup.


I’m going to build something like this….it should be pretty easy.

 

2.25" can flow the horsepower that most modified minis produce. remember that the limiting factor is the header-to-catback flange in most cases. You can have a 4" cat back but it won't make a difference if you have a 2.25" flange before it. (Truth be told it wouldn't make an improvement anyway).

 

This is so true. You'll hear a lot of people swear by 3" piping because it "opens up". It's a bunch of bull. If you have 3" piping from your headers all the way back, then maybe you would see a small difference. But really, exhaust isn't a real hinderance with Minis as is the case with most smaller displacement factory forced induction engines. OEM engineers know that they have to get the flow rate right when dealing with forced induction and as such usually leads to minimal gains when upgrading cat-back or mufflers while sticking with factory cats, headers, etc. Really, your best bet, if you are serious about making your own custom exhaust (which is hella fun btw), is to figure out which muffler sounds the best to YOU and then make your piping accordingly. Follow the same lines as the JCW setup and you should be fine. As far as the flanges go, that's beyond my expertise at this point. Maybe Pelican?

 

So bare with me on this comparison. I know it's an Audi and not a MINI, but just to talk about the mufflers.



The shop I previously worked at, the owner does some amazing custom builds. This exhaust is completely custom for this big turbo build that we had in. The mufflers you see pictured are Vibrant Performance. I'd suggest looking into them. It gave the build a very nice sound and nothing too loud. Adding resonators helped as well as you see towards the front of the photo above. As far as a flange, have you looked into doing a v-band set up on the exhaust instead? It's what we did for most custom exhausts and really helps with adjusting it and removing it when needed. Otherwise, I don't think we sell flanges so check out this site here.

 

Was you JCW exhaust resonated?

 

I had the resonator removed a few years ago. It sounds ok....but definitely not as good as most of the aftermarket exhausts i have heard.

 

my stock system was rotted and was ready to fall off ,here is what I did with my set up,, these are parts I had kicking around from other projects and header builds , I had a 2.250 j bend I sectioned into a y pipe from the cat back pipe, I had 2 flowmaster 2 chamber mufflers that I capped the outlets and cut in a half of a 2 1/2 u bend on each muffler and it be came the cross over for the 2 chrome tailpipes off a pair of 2006 gto mufflers ,, I did have to add a baffle on each muffler because it was real loud ,, but it has the right tone and not to loud ,no droning ,,gmonde

 

custom exhaust by www.gmondeperformance.com

 

When you do a custom exhaust and its more free flow an louder , you will tend to get a drone at speeds. The task is to sound louder and not drone. Good luck on the custom exhaust. Follow the line of the JCW exhaust and should be good.

 

Just to make a suggestion, if you do the single muffler only use a single outlet instead of the two you have in your posted photo.

Reason being is the added on outlet on the right will not produce much outflow so its more for looks than function.

Anyway, if you are making it different go for a single oval tip.

Please post photos of your project and of course let us all know how it sounds !

 

Yep, that's what I was planning...a single oval tip. I'm still trying to pick out a muffler, but hopefully I will find something soon. Yep....i will make sure to post some before and after pics and videos

 

on the first picture i see rods for lower control arms where did you pick those up they look awesome under there.

 

I'd suggest talking to the Magnaflow guys for muffler suggestions; they make quality stainless mufflers. Richard, the VP of engineering has been on many car reality shows (Gas Monkey, Chip Foose's show, and a couple of others doing custom exhausts). They can probably give you suggestions for the performance and sound you are looking for and probably have something in stock that would satisfy your requirements. I'm not affiliated with them; just a satisfied customer who helped in my Lotus 7 exhaust.