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New here and new with my NB year 2000, 1.8 and was wondering... Some models in this year seem to come with a six-speed gear box, mine with a five-speed. 1. Can they be swapped and, 2. Up to what model years might I do this with and is this a good thing? I read somewhere the five-speed is "better" performance. Also and, sorry if this is not the right area to post, but I was wondering if someone out there could recommend a place to get an aftermarket rear exhaust muffler with a little bit of a note as opposed to the current very tame sound. I am in Tassie so my options are very limited. Thanks heaps.

Yes you can swap to a 6 speed.
Usually people do this as they have increased power and the 6 speed is stronger. Apparently the 5 speed has a better shift.
Re the muffler, you can change for one that isn't baffled. I'm not sure what is available in tassie but you could just visit your local exhaust shop.

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Yes just buy one and swap it in.

Many prefer the feel of the 5 speed, and it already has pretty great ratios for the car, but you can fit the stronger 6 speed easily just bolt it in.

Dann

Given the choice, I'd take the 5 speed from my old NB8A over the 6 speed in my SE any day.

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The other thing is cost. A 6 speed is 10x more expensive. If you don't need the strength than don't bother.

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deep_notes wrote:Up to what model years might I do this with

Up to & including the NB8D, ie P4 revision with a 2004 build date, some of which had an early 2005 compliance date (but not the 2005 NC). But a 6 speed GB will cost about $1k, & for you in Tassie probably have added logistics issues, ie you'll probably have to resort to buying one from the the mainland with the associated shipping costs. Then you've got the unknown in terms of getting a decent 6 speed GB as well as being happy with the feel of gear changes, which tends to be variable person to person & GB to GB. Given aforementioned, for a standard NB8A like yours, it really requires a compelling reason.
Re catback exhaust, Town & Country in Geelong Vic do one that's popular - may be they'll ship it to you to be fitted locally.

IMO Stick with the 5 speed

Keep the 5-speed, Mark Hammond called it one of the best gearboxes of all time.

The manual version of the Aisin 6-speed in the NBs is a complete dog, reverse is hard to find, it's too easy to find 2nd when you really want 4th at the track and too easy to try and engage reverse when you really want 6th.

The Aisin 6-speed was used in Mazdas, Nissans and Toyotas. It was used in the NC too and in the Toyota 86 and still has way too many reported issues getting into 2nd when cold.

The Miataroadster SSK helps improve this a lot but it's still not as slick as the 5-speed.

Some MSM/SE owners in the US that do a lot of autocross events actually swapped out their 6-speeds for 5-speeds.

If you really want a 6-speed gearbox, this is the route you should take: https://kmiata.com/blogs/news/big-news-bmw-transmission-upgrade-for-your-miata

re the e46 gearbox, i'm still to see and hear back from them a message i sent them in May how the start motor is to bolt up without very modified exhaust headers and water feed lines for the BP motor.

Starter motor placement is swapped to the left side of the gearbox instead of the right (when facing the engine) and theres no advice on how to start it.

Lokiel wrote:Keep the 5-speed, Mark Hammond called it one of the best gearboxes of all time.

The manual version of the Aisin 6-speed in the NBs is a complete dog, reverse is hard to find, it's too easy to find 2nd when you really want 4th at the track and too easy to try and engage reverse when you really want 6th.

The Aisin 6-speed was used in Mazdas, Nissans and Toyotas. It was used in the NC too and in the Toyota 86 and still has way too many reported issues getting into 2nd when cold.

The Miataroadster SSK helps improve this a lot but it's still not as slick as the 5-speed.

Some MSM/SE owners in the US that do a lot of autocross events actually swapped out their 6-speeds for 5-speeds.

If you really want a 6-speed gearbox, this is the route you should take: https://kmiata.com/blogs/news/big-news-bmw-transmission-upgrade-for-your-miata

^ That is the summary right there.

I've got both an NB8A with the 5 speed and an SE with the 6 speed.

When I was looking for MX5s, quite a few of the 6 speeds I drove had horrible sloppy shifts. Even the good ones weren't as nice to use as the 5 speed. My 6 speed had a short shifter when I got it (not sure which one) and is quite tight and similar to the 5 speed to use. I did have a some trouble with crunching gears though until I changed the oil to Redline MT90, which transformed the box. Now its a joy to use. But finding reverse can be a pain sometimes.

The 5 speed is a great box and I don't think I've dríven a bad one. Unless there was a compelling reason to change it I really wouldn't bother.

Keep the 5 sp.Better shift, better gearing with the standard 4.1 diff fitted to your car.For road use that is just abut perfect.Changed my NA8A (so same box and diff as yours) to a 6 sp and because 6th is lower than 5th in the 5 sp also went to a 3.9 ratio diff.Great set up but not worth the cost for a road car,wouldn't do it again1

Peter.

I generally endorse the sentiments above, but I think the Bimmer route is only worth it for really biiiiig kw cars - you are really sick of replacing gearboxes that failed through sheer rwkw, and are prepared to throw lots of money at a long term solution.

I have run an NB8A as a road/race car with both 5 and 6-speed boxes. My NB8B racecar had a 6-speed.

5-speed: nice change, but weak. I broke 3rd, it gets a lot of use at motorkanas and at Wakefield, and after several years it gave up the struggle.

6-speed: not-so-good change, stronger, different gearing (noticeably punchier in 3rd and 4th). With the 4.1 in the NB8A it revs a bit harder than the 5-speed, but 3rd-4th-5th get more use, spreading the load. A better gearbox for a modded car that sees a bit/lots of track work, where 10ths can matter.

There are things you can do to improve the change in the 6-speed, but you would never swap one in for the 'knife-through-hot-butter' shift feel, you do it for the strength and/or ratios.

Lokiel wrote:Keep the 5-speed, Mark Hammond called it one of the best gearboxes of all time.

farking mark? All clever and sh*t making me google to make sure you were on about the hamster.. Is that his real first name?

Richard Mark Hammond....