6MPS Exhaust options

[TBDM]

I want to modify our 6 but am not keen to do the Dump Pipe until the car is our of warranty, which is another 12 months away. After haviing the car on the hoist and checking out the exhaust after the cat, specifically the y pipe bit, I was thinking about getting that remade as it does not look lie it flows very well. Im also wondering if anyone knows if the standard rear mufflers are very restricitve? I like the small note they give and certainly dont want anything loud or with any drone, a little note is ok but nothing too over the top.
So I am thinking about re-doing the pipework from the cat back to the rear mufflers, am I wasting my time without changing the mufflers or will it acheive nothing without the downpipe.
I have a hi-flow metalic cat sitting at home off one of these cars which I will probably throw on as well.
I can have all this done for the cost of parts and a carton so Im just not sure which way to go.

[rd415]

There are a few 6 here that have different exhaust systems. I have heard a CPe and I have a corksport, both give a nice external subtle note. From inside the car, I can only comment on the corksport, and that it has annoying drone at times. But I think overall the quality in particular and the sound most of the time outweigh the occassional drone. The more I drive it, the more I like it.

[rogwick]

I have the CP-E downpipe and a custom cat back installed on my 6. Fair enough if you want to wait for the warranty before putting in a downpipe as it may give you the typical turbo seal problems a lot of people seem to have (I have not experienced in mine...yet) I thought the standard 'Y' piece was a more like a curved 'T' piece and I felt it was a bit restrictive too. As Russell mentioned above the corksport exhaust is an option and a better flowing exhaust gas design. I opted to get a custom cat-back designed, fabricated and installed when I had the downpipe installed. Labour was all done in one hit to save me time, cash and hassle.

I can't comment too much about the standard mufflers being restrictive, but as a short answer I would say 'yes they are' IMO. The mufflers I have which are Super-cats are more of a straight through muffler, which, by rights, should deliver a better flow, thus additional performance. The amount of gains (if any at all) in comparison to the stock mufflers I honestly do not know, but that's just a personal opinion really. I've always thought the quieter the exhaust the harder it is for the exhaust gases to flow out, (being muffled).

In regards to exhaust note, it really depends on the individual really. Personally I'm not really a fan of a super quiet car. They're boring to drive, and does not really give you the passion of driving a sports car. In saying that, milo tin exhausts are annoying, loud, cheap and have 'hoon' labelled all over it. In conjuction with my two supercat mufflers I have 3" mandrel bend coated mild steel piping, one resonator located just after the DP, a second resonator located further down, which then split into the 'y' piece and into the two mufflers respectively.





The result (based on my set-up) is;
- A 'beast' on cold start-up (2,000RPM)
- Very quiet on warm idle.
- Sound and performance under throttle,
- Very quiet in the high gears cruising.
- At one point I was getting about as much road noise at 100kmph than I was exhaust note.

If you find yourself attending a cruise (WA) or meet and I'm there I'll show you mine. Toddy also has a similar exhaust but was designed by another chap. His is a little more louder than mine. Hope that give you some idea. If you have any questions about the above let me know

[TBDM]

hmm interesting, Looking on MPS Garage the corksport system in quite well priced, but the mufflers do look quite small and IMO would drone

I found these posts in other threads

If you're thinking about exhaust options, it might help to know that the stock MPS6 mufflers are a piece of engineering brilliance. Their design specifically matches the car to cancel droning and resonance and they do so with a loss of just 4kw more than after market hi-flow mufflers.

There are two flow restrictions in the stock MPS6 exhaust that have proven to give good gains when dealt with intelligently; the DP is one and it's covered elsewhere in these discussions. The other restriction is the T-piece, which is why I hate twin exhaust outlets on inline 4 cylinder engines.

If you can get hold of a well-made mid pipe that improves flow at the split, you can gain up to 17kw. By keeping the stock mufflers it will cost a fraction of a cat-back system, it will deliver about the same power gains and it will have none of the droning and noise issues. This configuration has been proven by an experienced race car engineer, but the idea has never gained traction because a bunch of CPe fanboys told the expert that he didn't know what he was talking about. He quickly stopped wasting his time on Mazda development.

It makes you wonder if the after market suppliers are only interested in maximising their profits, or if they feel obliged to produce products to meet the often poorly informed expectations of the market, even if that means producing products that are not optimal.

It's not the mufflers that are hindering flow, it's the T piece. The stock mufflers are only robbing about 5hp compared to straight through mufflers, but they offer the benefit of being tuned to suit the car and from a noise perspective will out perform every after market muffler.

If you're looking for more noise go ahead a change the mufflers, but you'll be lucky to see a 4kw gain. If you're looking for more performance, keep the stock mufflers and replace the mid pipe with a 3 inch into a low angle merge collector going out to 2.5 inch mandrel bent curves that step down to meet the stock flanges on the mufflers.

This low cost option has been proven to give a 19hp (14kw) gain atw, with little to no increase in noise.

Of course you could add a DP later and more than double that gain.

[Doug_MPS6]

Hi TDBM, I have the CP_e catted Downpipe and kept the entire stock cat-back system, although I had bought the CP-E catback stainless sytem which I still have but have decided to sell. The car runs well and is quieter than with the 3" SS system. While there is little doubt that the stock mufflers are more restrictive, KMH001 has said it pretty well. I'm not stressing about losing ~4Kw, and I don't want lots of blat and drone. The car cackles pleasantly a little bit on a cold start as a result of unburnt fuel in the DP from the rich idle setting, but in 15s settles to a nice quiet but purposeful sounding idle, and only barks a little, unnoticeable inside, when you goose the throttle for a sudden burst of power. It's as quiet as stock on normal road use. I'm happy with my stock mufflers. One could modify the T-section a bit, if one wished, but I doubt it's really worth stressing over as a one off job. You can have my CP_e 3" catback exhaust for a consideration, if you want to do a complete change, plus it mates up to the CP_e DP perfectly as well. I reckon its a better DP than the CS one as it is a single outlet and more compact unit. I didn't get any CEL's on installation either.

[TBDM]

Thanks for the replies, Im have the same feelings as you Doug, not really to keen on a noisy exhaust and I guess for a loss of a few KW its best to stick with what we have go. So I guess if we want to do anything its going to be the downpipe.

[2XS]

You can save yourself a few dollars by re-using the std rear mufflers.

Having the DP done at a separate time won't cost the earth either.

I did a full TBE excluding the rear mufflers on Penguin740's car. It has a note under power, but very minimal at idle, if at all. It is a full 3" system with 1 cat and 1 resonator.

[TBDM]

Ooh that mid section looks nice and was just like what I originally had in mind.
I might just save my money and do the FMIC + Dump + Cat + Mid section all at once, depends on how much $$ I have left after my bathroom renovation

[esp22]

I have the CP-E downpipe and a custom cat back installed on my 6. Fair enough if you want to wait for the warranty before putting in a downpipe as it may give you the typical turbo seal problems a lot of people seem to have (I have not experienced in mine...yet) I thought the standard 'Y' piece was a more like a curved 'T' piece and I felt it was a bit restrictive too. As Russell mentioned above the corksport exhaust is an option and a better flowing exhaust gas design. I opted to get a custom cat-back designed, fabricated and installed when I had the downpipe installed. Labour was all done in one hit to save me time, cash and hassle.

I can't comment too much about the standard mufflers being restrictive, but as a short answer I would say 'yes they are' IMO. The mufflers I have which are Super-cats are more of a straight through muffler, which, by rights, should deliver a better flow, thus additional performance. The amount of gains (if any at all) in comparison to the stock mufflers I honestly do not know, but that's just a personal opinion really. I've always thought the quieter the exhaust the harder it is for the exhaust gases to flow out, (being muffled).

In regards to exhaust note, it really depends on the individual really. Personally I'm not really a fan of a super quiet car. They're boring to drive, and does not really give you the passion of driving a sports car. In saying that, milo tin exhausts are annoying, loud, cheap and have 'hoon' labelled all over it. In conjuction with my two supercat mufflers I have 3" mandrel bend coated mild steel piping, one resonator located just after the DP, a second resonator located further down, which then split into the 'y' piece and into the two mufflers respectively.





The result (based on my set-up) is;
- A 'beast' on cold start-up (2,000RPM)
- Very quiet on warm idle.
- Sound and performance under throttle,
- Very quiet in the high gears cruising.
- At one point I was getting about as much road noise at 100kmph than I was exhaust note.

If you find yourself attending a cruise (WA) or meet and I'm there I'll show you mine. Toddy also has a similar exhaust but was designed by another chap. His is a little more louder than mine. Hope that give you some idea. If you have any questions about the above let me know

do you get much drone with your system?Thanks

[rogwick]

do you get much drone with your system?Thanks

On cold start, yes. Very loud and a fair bit of drone (granted its idling at 2,000RPM though) But once warmed up and also cruising, no, not much drone at all. Typical beefy note exhaust but minimal drone due to the two resonators I had fitted. I used to have a catback exhaust with a cannon muffler on my pulsar, that had drone!!