Restriction In The Exhaust

[rondofj]

Thinking of buying this oval veilside Jasma muffler as well but worried it will be much louder than my Xforce oval (I know its jasma approved, but the body is not too big..), it looks to be free flow?

What do you guys think?

[GTSBoy]

It'll probably be louder as you suspect. But at least there will be no restriction.

Just do it. if you don't like it, move it on. By the same token.........I don't think there could be any suspicion that the Xforce oval is restrictive. A straight through 3" is a straight through 3" in terms of what it can flow, give or take a few % point here and there for different perforation styles. So why not put your existing rear onto the cheaparse system from the previous page? If you're going to start cutting and shutting exhausts, you might as well cut up the one you already have and don't like.

By the same same token, which not just buy a decent 3" mid and stick that into your existing system in place of the shitty one that's on there now? Sounds like less f**king around than any of the options you have come up with or that I listed above.

[scotty nm35]

Neither way will likely fix your power issue, but I guess you need to follow your tuner's instructions no matter how much it costs in wasted time and parts. At what point do you pull the pin though?

[GTSBoy]

Yes, well.....we shouldn't talk about the catalyst (elephant) in the room.

[rondofj]

Well.. I will get that cheap arse exhaust, at least the main element, (the gutted catco cat) is there as well as the 3" mid-muffler. I wont take that ugly canon though. I might just buy the Jasma oval above if I don't find anything better.

Even Yavuz said my rear muffler might not be such a problem, but the cat definitely.. But you can see from previous pics the Xforce has a small hole outlet. If they fail to deliver results and come up with something else 'restricting my car',..well, time to move on...

[XKLABA]

I don't know why people run the risk of a $10k fine for 0 performance gain by gutting the cat, when for a couple hundred you can get a good cat that flows more then you need, on top of that when the cat "ignites" it helps keep the gas hot and hot gas moves faster then cold

I had an 80mm decat made for my 32 for drag racing, went to the drags did a run then changed to the decat did another run and they where both exactly the same time and speed, if your cat is a restriction then buy a new one that isn't

[hy_rpm]

Looks ok and fairly straight thru inside the veilside muffler

Also the bigger the rear muffler is the more sound it will suppress Aslong as it's still true 3inch straight thru

And your starting to head over 20psi and close to 300rwkw so the 2.5inch neck down in the rear will start to hurt power up top as 2.5inch is only good for 250rwkw

[rondofj]

Bought me a present, 3 inch used gutted cat and the Veilside Jasma oval muffler 5-6 threads up, its 3.5 inch straight thru however. Body size is 6X11X14.5 long in inches, my current xforce oval is 6X10X16 long so hoping the replacement wont be much louder.

Now need to find the largest 3 inch oval mid-muffler I can cram under there, any suggestions? ;-)

[rondofj]

And measured the guts of my xforce oval- 2.75 inches , well at least got a replacement now

[GTSBoy]

I think you'd be surprised how much you can flow through 2.75". That won't have been your restriction.

Edited March 29, 2014 by GTSBoy

[rondofj]

So u saying no need to put it on? What about my 2.7inch mid muffler necking on one outlet? Well it actually looks like it maybe 3 inside just the pipe is necked down at joint..? No idea why

[Badgaz]

i'm thinking of getting one of these ones, could be a nice option.

http://www.adrenalinr.com/productdetail.php?productID=511

[GTSBoy]

So u saying no need to put it on? What about my 2.7inch mid muffler necking on one outlet? Well it actually looks like it maybe 3 inside just the pipe is necked down at joint..? No idea why

Not, not saying that. Let's face it. The car used to make more power, now it makes less. Either the PowerFC sucks or the cat has a problem. The mufflers haven't changed, therefore they aren't the cause, is all. Bigger is always better (if perhaps louder), so go ahead and redo your exhaust. But just don't expect to identify what the actual problem was if you change everything all at the same time. If you only swap out the cat for something that won't be a restriction, and redyno and it all comes good, then it was the cat. Same for any other component. Change all of them though, and it comes good....and then wonder which one was the bad one, or maybe if it was the sum of the parts. Having said that last bit, re-read my 5th sentence.

[rondofj]

Lol the power FC cant suck, it is a constant and proven in many cars. The tune can suck of course, and in my case as mentioned its had timing retarded big time everywhere. And power (lack of) been suggested to a restrictive cat. And of course its cheaper to replace the exhaust components in one go and have a touch up tune, and if it makes power then u know its the combination of these components that was the problem but wont be able to identify which one.. Which doesnt really matter when you are able to pick this cat for 30bux and Veilside oval for 50..

[GTSBoy]

Point was....the exhaust components behind the cat didn't change, and the only other significant change was the PowerFC. So it had to be either that, or the cat shat itself.

[CEF33Y]

Any updates?

[discopotato03]

If you want quiet and free flowing ring Kirawee Mufflers , my exhaust is 3.5 to 3" necking back through a 200 cel Xforce cat and the mufflers are I think Redback . The rear is 20" long and something like 6 x 11 . They can get them in 3.5" as well . It fits up very neatly and the single 3" outlet looks really conservative .

A .

[skylinecouple]

If it were me I'd replace the exhaust as it is obviously bothering you. Don't you just hate it when you truly believe something isn't right and 6mths later you wish you had changed it ? Seems stupid to get a tune then end up changing the exhaust anyway. Do it once, do it right. I have just changed my dump pipe from 3" to 3.5" using the cat as a step down. The difference is chalk and cheese. Whoever said a bigger exhaust slows down the flow has rocks in their head. Revs faster harder, more power everywhere from idle to full boost. Strangely, it is quieter. Now I want to go full 3.5" all the way to see what my little 3071r is capable of.

[rondofj]

Update- cat replaced with hollow 3" compliance cat (for now) and necking in mid muffler eliminated. Drive feel on road was noticeably punchier n free-er on mid-high rpms. Then after touch up tune- a dissapointing 280rwkw at 22psi dropping to 18psi. Is this why I made low power? Precision 5558 on 98/ Rb25.

Previous boost drop was 2psi, now its 4 psi?? Only 10kw gain from previous 270rwkw at 20psi. But hugely different drive-a lot punchier n snappier in all gears and a lot more torque/boost in low rpms from feel - lighter throttle input required in low rpms. See dyno sheet.

One big problem is that during downshifts as in overtaking or motorway pulls from 4th to 3rd or 3rd to 2nd there is a massive power loss for 3-4 secs and then it suddenly boosts and pulls hard as normal. During this time it is like 50-60% down on power -like hitting a brickwall or NA yaris/civic spec torque. It ONLY happens on downshifts not upshifts. Is it tune related or a BOV or boost leak? Yavuz and Mark have confirmed the tune is as good as should be.

[89CAL]

Thats odd. Did they play with the tune much after you fixed the exhaust? I would expect it would need a bit of playing around with the tune, not as much as if it were a MAP based ECU

The precisions are ball bearing arent they? Sounds like it cant be a turbo issue, but it nearly sounds like when you drop a gear the turbo takes forever to get up to the speed it should be at. This makes me think its ECU related, as if its going to cells that the car never really reached before and the tuners just made safe just in case it ever did unexpectedly Even a boost leak it should sound like it wants to take off.

Thats certainly a strange one.... but the fact that you have gained power on effectively less boost (up top) and the better driveability at least proves that the exhaust was a problem