Custom Exhuast?

[asps91]

Hey guys, Just looked for something relating to my question in regards to custom exhuast systems, but i cant find anything which answers my questions.

Has anyone had experience with a custom 70mm single exhuast system fabricated at a good exhuast shop and have they noticed any power gains compared to others with bolt-on pre-fab kits.

I ask this question as with my old mk4 supra, the best gains were always seen through the custom systems rather than pre-fab bolt on jap exhuasts. Of course the numbers fluctuated as a result of good workmanship.

If i have said something stupid or if there is another thread like this. Please refrain from the flaming. I at least made an attempt using search feature. :)

[vyets]

GO find a 70mm resonator and muffler first. Unless you want to fabricate that too, they're hard to find and originally I was looking to go custom 70mm.

[ludecrs]

YOu might find this interesting.



not happy with the tuning progress today. lost 5hp atw compared to before and this is after doin:
-head porting
-3in straight thru exhaust
-t1r light weight crank pulley
-new valve springs and new titanium retainers

will go back on the dyno tomorrow again to compare against the 70mm exhaust, failing that, it would mean the head porting did not work


Source: FireBalls N/A SuperLap 2010 Build Up Thread (http://www.s2ki.com/forums/index.php?showtopic=784311)

[asps91]

Has anyone dynoed custom 2.5 inch, straight through?

[JAP-S2K]

I think your asking a good question, but i don't think you'll get many/if any answers. As the factory system is extremely good. And to achieve better results, lots of R&D is required. That's not saying that getting more power isn't possible from a custom. I have in fact seen a custom 63mm system not make any gains whatsoever. It made 1hp at the very end of the rev range. So not a great gauge, considering the variances you can get just from a dyno and/or weather. It's more the fact that a good quality custom (stainless) system with mandrels bends, will nearly set you back as much as an off the shelf item that is proven. Take the T1R 70R stainless system. Like it or hate it, it's probably one of the best bang for buck, with good proven gains, remember that a good gain is +5 to 10hp. The risk you run with a custom system, is it may not get you any gains and in fact you could loose power. If this is the case, you stuck with an overpriced, loud under performing exhaust.

[jbird]

The most you can hope for in an exhaust is:
1. More noise
2. Less weight

There's two that I think are at good prices for what they are. The ASM has proven gains of around 10hp. The HKS unproven, but sounds awesome.
If you can find someone in Sydney to do a job cheaper than that then go for it. But like vyets said, its hard to find a decent sounding muffler and resonator.

HKS 75mm single exhaust - about $600 US from Evasive + shipping.
ASM re-conditioned 70mm single stainless - about $1350 US from GoTuning + shipping

[bankids]

story began with i borrowed a stock from eric, and he's going to sell his car with all the stocks so i have to find myself a exhaust to use. I had a skunk2 70mm for jazz and then i decided to custom make it to fit my s2k. (I'm so broke atm, can't afford decent branded ones but i don't want those cheap ones off ebay.)
i went to a good exhaust shop and cost me 120 to get the modified to fit my car.

compare to stock exhaust, the one i got is:

much louder
not any quicker
never been pulled over by cops but got 2 times in a week after exhaust installed....now i have the silencer on,,,,looks so gay(i think airflow is shitter than stock with the silencer on)

looks bad with my kit (charge speed wide body..)

also for na, there's no back pressure..


forgot to mention it is lighter and might be good for turbo application.

also the sounding is kind of good(my mate likes it but i thought it sounds like wrx....)

[keeff]

have a look at autospeed thay recomend magnaflow mufflers have shown 20 hp more on there dyno

[vyets]

have a look at autospeed thay recomend magnaflow mufflers have shown 20 hp more on there dyno

ah yea.. thats not happening

[jbird]

ah yea.. thats not happening

+1

Maybe on a V8

[keeff]

well i have seen this kind of perfomance boost from changing mufflers on motor bikes and the s2k is tuned very differently to a v8

[JAP-S2K]

yeah still won't happen! 20hp gain, No exhaust/header combo will net you such a gain. And i'll near guarentee you'll lose power by installing a magnaflow muffler. You are in fact correct about saying S2K are differently tuned to a V8, we'll never see mod gain increases like 8's do.

[keeff]

well thay say the standard mufflers are very restricting but the s2k is already at a high state of tune so difficulte to improve on power means dollars and i dont want the extra noise

[jbird]

well thay say the standard mufflers are very restricting but the s2k is already at a high state of tune so difficulte to improve on power means dollars and i dont want the extra noise

The muffler restricts the noise and plays very little in restricting power because by that time the velocity of gases would have slowed down a heap from the piping size/cat/resonators and finally the split into the two mufflers - and hence robbed power along the way.

To see any gain you'd need to change the whole system. The extractors/header are a good design from the factory if a little heavy.

Worthwhile upgrades include Toda/Amuse/J's Racing/ASM
Test-pipe/high flow cat
2.75"/70mm cat-back single exhaust.

If I had a decent budget to modify I would buy a 70mm single ASM exhaust, because it is quiet yet loud on full throttle. Toda header. High flow cat of some description. Finished with a tune. That would probably see about 15-20hp if not more and a good boost in the mid range especially.

[vyets]

apprantly toda header isn't that good. however J's has come out on time almost every time.

[jbird]

apprantly toda header isn't that good. however J's has come out on time almost every time.

Touche....I think I remember someone said they crack. But they do make good gains especially around the mid range.

J's SPL it is....