I've picked up a 2005 R53 yesterday and drove home 150 miles (3.5 hours thanks to thunderstorms and heavy rain at night).

The car is great but the exhaust noise level is obnoxious. The seller has decatted the exhaust (with an O2 sensor bypass) and installed an aftermarket exhaust with a single muffler on the left side.

What is the best option to reduce the sound level:
- change the header to install a cat back?
- change the exhaust for a dual muffler resonated setup?
Both solutions would have similar costs (~ 1,000$ parts).

The car will be my wife's and she is adamant it is too loud (I would agree, even though I have hearing loss issues).

What manufacturer would you recommend? I've read good reviews of the Milltek system here regarding the noise control.

Thanks for your help!

 

I only have two experiences with my own recently acquired R53; the "custom" setup installed by the original owner -and- both versions of Milltek's catback system. The former being much too loud plus (um) less than attractive and the latter being a high quality manufactured product. As outlined in my own thread topic starting in post #30 here, I initially installed the resonated version for reduced total dBA but subsequently replaced the res-pipe with Milltek's non-res pipe. Mine has aftermarket header with flex pipe and cat, however the cat flange to res-pipe fitment put the top of the resonator can too close to adjacent tunnel above, thus I had vibration rattles when engaging 1st gear and certain resonant frequencies. Now with non-res pipe installed, no rattles whatsoever. I'd prefer a bit quieter but it's not obnoxious. Depending on yours, either one might work well for your wife with the res-pipe version likely better suited for her preferences if there's sufficient clearance.

 

Yeah, agreed.
I put a Miltech system on my 05, JCW. Slightly louder than the JCW exhaust, but definitely not objectionable what so ever.
Well built, fits well, all stainless steel. One glass or steel wool packed muffler (some call it a resonator) in the main tube, then two more normal mufflers at the back of the car. Normally sold at a fair price. Sometimes can be found on sale.
Little to no loss in power. In fact, it eliminated a flat spot in the power curve in my engine.

Mike

 

I spent a long time shopping exhausts. I had the factory system on my car when I bought it. I was torn between Invidia and Milltek, ended up with Milltek. I bought the non resonated and am happy with it, but it's not quiet. With the cat removed, you might be wise to go with the resonated version.

Milltek has some great sales every 3 months or so, 10-15% off plus free shipping, and sometimes even better, although with all the supply chain disruptions and raw material price increases, they may not follow the normal pattern.

 

Thanks guys! Now, should I start with the header replacement or the catback exhaust replacement?

 

I wouldn't run without a cat, but that's me (and whatever your local regulations require). I also don't think you'll be happy with the sound of the exhaust you have. I would plan on doing both, but if budget dictates, I'd start with replacing the cat. You might find a shop that can install a cat for you without doing a full header replacement, although there may not ultimately be much savings there. That would allow you to decide if the noise reduction was enough to allow you to live with the existing exhaust.

 

Find a used stock exhaust set up with cat. Done.

 

I'll be starting with the cat. I've ordered the Magnaflow universal cat compatible with the 2005 Mini Cooper S and will get it installed next next. I'll report on the sound adjustment.

 

Also look at the tips that EuroThrasher gave me in my topic > https://www.northamericanmotoring.co...ml#post4581688

Sound deadening in the right places makes a major difference.