Exhaust Cat Back

[petross]

Hi guys,

I have a turbo sitting at home. Just did the oil return on the sump (which my dad n i havent put on yet), and now looking for a good exhaust place to do a 2.5inch stainless steel or a cheaper solution, though quality, from the cat back??

And also a good quality muffler, where the pip goes straight through?

If anyone has done one and approx. on how much it would cost would be greatly appreciated.

Thanks.

[pcmx5]

It would help greatly if you indicated where the hell you are!!!!
Peter

[93_Clubman]

It would help greatly if you indicated where the hell you are!!!!
Peter

Burwood, VIC

d-mag might be able to help with that - he had a custom 2.5" system on his old turbo Clubman.

[de Bounce]

It would help greatly if you indicated where the hell you are!!!!
Peter

I think pcmx5 is indicating that Petross needs to add his location to his profile

Petross - It is in the User Control Panel under Edit Profile - Location

[Fatty]

i and a few others have had 2.5 inch mandrel bent exhausts done at unique exhausts in dandenong. i was very happy with mine, picked up 20rwkw on my mild low boost turbo just with this exhaust and a timing bump. however apparently the business has changed hands so i'm not sure if they still have the same staff and knowledge base / quality.

the other place people often praise is town and country in geelong. i chose not to go with them as they didn't have much experience with turbo mx5's at the time but apparently that has changed now, and they've done at least 1 that i know of with very good results.

[Benny]

A 3" should pickup a fair bit more hp and not be a whole lot louder.

A 3" system would defintely be a good thing, except that it's a VERY tight fit in an NA or an NB, and it would rattle like crazy as there's very little room for it to move.

I've talked to Daniel Deckers a few times about this, after seeing him put a 3" system on a race car, and he showed me what a difficult fit it is and he reckons the banging would drive you crazy in a street car.

[petross]

That's what i would have thought too, a 3" exhaust. Though, the guy at AVO said 2.5" from the cat back, because with the 3" it will not have as much power.... I have a 2.5" tip with it opening up to a 3".

[93_Clubman]

petross, adamjp made an interesting post of exhausts a while back - starts off basic but goes into exhaust for FI applications & 2.5" V 3.0":
viewtopic.php?f=76&t=22540

[GS]

According to the FAQ on their website, Enthuza exhausts have dyno tested their Miata exhausts and recommend that going from 2.5 to 3in on a high boost turbo doesnt result in much more power, but gives you a lot quicker spool.

The clearance around the firewall isnt great on turbo'd MX5's, so from what ive read increasing the downpipe size from 2.5 to 3in causes some fitment issues. But if set up right a 3in cat back shouldnt be too bad.

What diameter pipe should be used with my Miata?

I have dyno tested all of my exhaust and this is what I have found works best for these Miatas: (accounting for sound and horsepower):

* M1 Racer and M2 Speeder 2.25" = Normally Aspirated Miatas and 6 psi or less Supercharged Miatas (5-8 hp increase) (stock size is 2" and 2.25" will not affect low end torque). Miatas have a relatively low compression engine which is not affected by backpressure. Through the dyno tests the 2.25" works very well in increasing both horsepower and torque.

* M1 Turbo Racer 2.5" = Turbocharged Miatas @ 12 psi and less (19 hp gain over 2.25")

* M1 Turbo Racer 3" = Turbocharged Miatas @ 12 psi and higher ( 3 hp gain over 2.5" but a 400 rpm quicker spool up)

http://www.enthuzacar.com/faqs.html