Exhausting

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Regardless of how you feel about it track day noise limits are with us and only likely to get more restrictive as time goes on. Despite the benefits to the local economies located close to racing circuits it seems a common trend that pressure from residents and local authorities mean that noise limits are being more strictly enforced. Even standard road cars with valved exhausts are marginal particularly on drive by limits and aftermarket exhausts will certainly struggle.

Having had a few issues with noise in the past, including one track day that lasted 5 laps, I’ve been searching for a longer term solution that would work over a range of noise limits.

The first part to be replaced was the Janspeed racing catalytic converter which had failed causing a really nasty resonance in the exhaust. Rather than opt for another racing cat (which have a reputation for failing) I had 1320 Mini fabricate a “tomcat”. The Tomcat is a modified stock catalytic converter which bolts up between a tubular manifold and cat-back  exhaust.

The Milltek cat-back exhaust is a fairly common after market choice for the R53 and isn’t the noisiest of systems but I decided to replace it so that I could easily add additional silencers should a circuit be operating a particularly restrictive noise limit (the twin tailpipes make it almost impossible to use any of the common noise reduction solutions).

Replacing the rear section of the exhaust also seemed like an ideal opportunity to simplify and lighten the system at the same time. The R53 Mini has the battery mounted in the “boot” because of the limited amount of space under the bonnet compared to the normally aspirated cars. In the later R56 turbocharged cars the battery is location under the front scuttle which means the exhaust is a much simpler straight-through design. I wanted a straight-through exhaust but also didn’t want to move the battery away from it’s current location, meaning a smaller Odyssey battery was my only choice.

Magnaflow Muffler
Magnaflow Muffler

I decided to base the exhaust around the largest 2 1/2″ inlet/outlet straight through muffler I could find that would fit under the boot section of the car.

1320 Mini Fabrication
1320 Mini Fabrication

The next stage was to take all of the parts over to 1320 Mini to get them to fabricate the exhaust and modify the battery box.

Exhaust Rear Section
Exhaust Rear Section

The result is a very neat solution which still bolts up to the Milltek exhaust and uses the stock hanger locations. Having a plain outlet from the muffler with no tip or trim means i can use additional silencers like the Decibel Devil.

Decibel Devil
Decibel Devil

The battery box needed a few coats of primer, some sealer and finally some top coat to finish it off.

Battery Box
Battery Box
Battery Box
Battery Box