Race twin exhaust

At motorway cruising speed on part throttle, it's no louder than the standard exhaust. You can still hold a conversation or listen to the stereo. Like all GTAs, it's mostly tyre noise you can hear. Only when you put your foot down and open the throttle, or lift off on the over-run, does it become vocal...

On the subject of cutting open the old exhaust, I did this on my first GTA, and it did make a difference to the sound, didnt feel any different though, maybe because there was no longer and 'flow' through the box. The only other problem I has was...the original box is aluminumised steel so it doesnt corrode easily, when it was welded back up, it began to rust at the welds being migged, from inside and out due to moisture in the exhaust on cold mornings, so even painting it didnt help.

On the subject of my new exhaust, I can get a device called a divertor valve, but they cost around £100. Its a billet steel 2.5" valve (much like a throttle butterfly) with an actuator much like on a turbo, that goes in the main tubing from the turbo, and is controlled by vacuum off the engine, so at part throttle and idle, it is nearly closed reducing the sound, and at zero vacuum or boost, the valve fully opens derestricting the exhaust.

.but at normal idle, it will sound like a normal exhaust (but also not spool up the turbo as quick), so you ending up spending all that money, and most of the time when you are driving it wont sound much different to the original....horses for courses!

. It could also have an MOT mode where an entire roll of rockwool loft insulation is inserted just far enough in to muffle any last lingering whisper and satisfy even the most stringent tester.
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Thats a good idea!. You could on the Race twin system, slip a 3" rolled tube of insulation into the exhaust bottom tube, and it wouldnt be noticed by the MOT and it would reduce the sound massively...and afterwards it could be poked out..

I have to stress though, even though Justins video sounds good, it still doesnt tell you how loud it is. I many of you have heard aftermarket Subaru Impreza or Nissan 200sx exhausts, its around the same volume as them. If it wasnt for the turbo design, and long restrictive manifolds of the GTA, then it would be quite a bit louder.