Whilst I'm aware that this is a thread topic that has come up time and again

(there's one on this very page pertaining to a similar question for tubbies), I have a few of questions.

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Firstly, I've always liked the fact the turbo exhausts have the two back boxes, and the only NA exhaust I'm aware of that has a similar thing is the Japspeed, an exhaust system that appears to be only appropriate if you are either already deaf or simply don't care about your hearing.

My question is, are there any quieter double box exhausts for the NA, or is it possible to get some kind removable baffle so when I'm on the motorway or whatever I don't give myself a haemorrhage?

Secondly, failing the double box idea.

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which exhaust is best/most sensible for an NA? My old Rev4 had a slash cut Mongoose, an exhaust I'm given to believe is the most sensible of the aftermarket exhausts, and even that was a bit drone-y on the motorway.

I currently have the stock exhaust on my Rev5 and want something that will be lovely and burbly around town, epic on WOT, but controlled at motorway speeds so I can actually hear my music/the other half.

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Finally, getting an exhaust fabricated at an exhaust shop is my final resort.

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how expensive is this likely to get? I realise to fully comply with my above criteria, all kinds of butterfly valves and bypasses etc etc could be used, things I presume would make the price go sky high.

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but how much is it likely to cost to have someone make a quieter version of a Japspeed style exhaust?

Many thanks!