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Hi There, I recently joined the forum after purchasing my NC2 Touring M6 earlier this year. I have been doing a lot of research about exhaust and tune to determine if it really is bang for buck, or a lot of effort and coin for little gain.

I think I've hit a combination that will meet my objective of notable gains in power and torque, and not making the exhaust louder.
I believe the biggest gains are to be made in the header, and not the midpipe and rear section? - am I right? I am looking at using the Goodwin Racing Header with the standard midpipe and rear muffler. I am not so much concerned about exhaust note, but understand the car will be a bit louder with the header.

I could do this as a standalone but am also considering an ECU reflash by one of the forum sponsors MX5Parts. Has anyone any experience or comment having gone this path?

My understanding the standard car makes @ 90rwkw. Is it unreasonable to expect a gain up to around 108rwkw with these 2 mods? It sounds a bit high, 20% rwkw gain and corresponding torque?

I'd like to hear from anyone who can share thoughts of a similar combination and either real measurable gain or SOTP experience.

Charlie Brown, Dan & Regie have posted on NC exhaust mods in following:
viewtopic.php?f=19&t=69806
viewtopic.php?f=29&t=49533
viewtopic.php?f=18&t=67315
viewtopic.php?f=29&t=59555
viewtopic.php?t=71567

That is awesome!!!!. Not sure what I was searching for now and missed these nuggets of gold.

After reading, I believe I am on the right track thankyou.

Forum search function is not optimal - fortunately I'd posted those before & the post hadn't been deleted, so knew where to look. Better to use Google to search this forum by just adding search term to here: https://www.google.com.au/#q=site:http: ... artalk.com

Yes Goodwin or Racing Beat headers will work magic for you!

I have the full goodwin setup - Headers, mid pipe and RSQ by the sounds of it, it will be too loud for your liking.

Headers only with the rest of the system stock will produce more noise, but wont be much louder than stock (has a really nice note)

If you plan to use your stock mid pipe, you will need a O2 sensor bung welded in just after the cat, easy job for an exhaust shop.

If you are handy on the tools, they aren't too hard to install, I've done 6-7 sets now

as for the power gains, the headers will bring the most noticeable power gain, ECU is optional and can be done down the track (ECU will gain 2-3rwkw at the most)

Where are you located? If in Sydney, happy to take you for a spin in my car

Thanks Regie and 93Clubman for the help.

I am in Melbourne so thanks for the offer Regie but a bit far!. Good to now about the ECU tune, at $795 I don't see 2-3kw gain as a bang for buck mod as I would also anticipate the torque gain to be negligible.

Interestingly I am also considering the GWR 'street' header which also has a cat fitted. I suspect though that will be down somewhat on gains that the non catted header would deliver. As for the O2 sensor bung, that is definitely an exhaust shop job, not in my skillset.

The catted header won't fit our RHD cars.

It's the race or nothing pretty much. Some people over here have fitted the long tube headers, but it involves a lot of hammering to make it fit.

When it comes to fitting that bung, make sure it's installed above horizontal to keep the sensor happy and avoid fault codes.

I have the Ceramic Coated Goodwin Header and it's the best engine performance mod you can do but the addition of tune in my opinion completes the package.
I have a Tune from Dynotronics in USA using ECUtek.
More power, RaceRom is cool, and I love the autoblip feature.
The throttle is more responsive and I also get a higher rev limit.

Definitely worth the cost in my opinion.

I'm in SE Melb and can take you for a spin if your interested.

pie5 wrote:I have the Ceramic Coated Goodwin Header and it's the best engine performance mod you can do but the addition of tune in my opinion completes the package.
I have a Tune from Dynotronics in USA using ECUtek.
More power, RaceRom is cool, and I love the autoblip feature.
The throttle is more responsive and I also get a higher rev limit.

Definitely worth the cost in my opinion.

I'm in SE Melb and can take you for a spin if your interested.

PM sent!!

Can anyone comment on the implications of deleting a catted header? From my understanding in Victoria it is flat out illegal, whereas in New South Wales you are required to get an emissions test done. I know there are a number of people on this site that run the catless headless regardless of roadworthy, but if possible I'd like to not go down this route.

Also, what changes are made to the exhaust when supercharging or installing a 2.5l? Is a stock setup run to pass emissions, then a custom exhaust fitted?

keito wrote:Can anyone comment on the implications of deleting a catted header? From my understanding in Victoria it is flat out illegal, whereas in New South Wales you are required to get an emissions test done. I know there are a number of people on this site that run the catless headless regardless of roadworthy, but if possible I'd like to not go down this route.

Also, what changes are made to the exhaust when supercharging or installing a 2.5l? Is a stock setup run to pass emissions, then a custom exhaust fitted?

Car has two cats, one in the header and one in the mid pipe.
My understanding is the main cat is the one in the mid pipe and the cat in the header is only required/needed for cold startup.
When you put the performance header in and relocate the O2 sensors then it shouldn't code.
If it's tested warm it should pass an emissions test but not a visual one.
Roadworthy in Vic probably depends on how strict the the garage/tester is.
My understanding is a supercharger will kill the catted header quickly.