^^^^^ this. and its mostly 2.75 on an LNF.

 

I guess I know alot more then you bud, since I knew that the LNF exhaust is 2.75", the muffler is a bigger restriction then the pipe going from 2.75" to 3" is minimal gains.

A muffler is cheaper then a whole cat back.

Now go take your foot out of your mouth.

 

calm down there pal

 

lulz.. those are some REALLY odd crush bends .. first time i've ever seen a crushbend not get pinched on a 90+ degree bend

OP you'll probably gain a few whp.. .. what HHRsouth way saying is you'd probably gain the same amount of power from just doing a muff delete or getting a more free flowing muff.. but honestly like you said no one has proof aither way so have at it

 

Fixed and toned down a little just for you

 

thank you haha

 

Last time checked exhaust is nothing more than vanity on turbo cars. Anyone I know with turbo vehicles goes cat less with no muffler (for weight and sound).

anyone want to prove me wrong?

 

the stock exhaust isnt crush bent... Thats why it is one hell of an amazing stock catback exhaust. and yeah, rallycobalt06 and I measured the pipe diameter when we took out the stock DP... it was very very close to about 2.75". The muffler is probably the most restrictive piece since its a big hollow container and changes the flow a bit before exiting.

You best bet for the best exhaust to give you the highest whp gain would be one with fewer bends, I'd say a cut out exhaust.

I think if I did an exhaust though, Id do the one in that picture. It looks purdy!

 

Really, now - isn't the total flow/flow restriction on a turbo'ed car going to be a function of the first/most major restriction seen in the exhaust path? On a stock catted car, that will be the cat and that end crimp - everything stacks up ahead of that, and everything else after that becomes irrelevant unless there's a much more severe restriction that will cause further reduction in flow capacity.

I think it'd be utterly useless to do this test on a car with the stock dp, since exhaust backpressure to the turbo will not be reduced, unless there's some magic there? Any magic? I could use some if there is....

 

As much as I wanted to test the stock catback vs my 3" treadstone straight pipe catback my clutch started going south on the first dyno pull. No results

The car does indeed spool faster with the catback but im willing to bet the actual whp gain is minimal. It sure does sound like it's faster LOL

 

new hahn system sounds great fits great. I put one on for a customer last week. Personally I would not run one on an LNF ;I do however run an LNF stock exhaust system off a hi flow bullet cat ZZP longtube ( a very good piece for sure) on a TVS LSJ with an LSJ muffler and 320 wheel is not a problem.
On my car previously, the 3 inch was hopelessly noisy no matter what I did, other than an LSJ muffler on the end. and was a beatch to align so it would not hit, although I did get that worked out. The 3 inch doesnt package easily, Hahn have done a very good job on this latest system for that.

 

Please let me know where I discussed diameter of piping being critical to gains. Because I didn't. It also has nothing to do with anything I am asking. The exhaust could be 2" or 4" my concern is just the stock catback and the gains any free flowing exhaust could net.

I also never mentioned price.

Please understand my true intent before you take a stand in something I'm not even arguing against. Hell I even agreed a catback may even net 1hp and that is fine as I just want to see if the bends and muffler piping as a whole leaves a lot to be improved or nothing.

I'm not here to tell people with stock exhaust that they are stupid or anything. Hell if I can prove 0 gain I would be happy as it could save people some money.

With that said please bring it to pm if you really feel the need to argue, I will quit typing from the phone and log on to do so.

 

the direct answer for the OP is "no"

most road wheel dyno work is notoriously unreliable/unrepeatable for a quasi scientific comparison. a climate controlled dyno cell is better.

the cause and the question is an honorable and just one to pose. so my answer is above.

 

I agree and it would be a very small sample size with only about 6 pulls total. If the graphs show no changes the dyno will still ne fun as ill have it for a while tuning my buddies csrt4 anyway.

My real goal is to see if its possible to bring any kind of evidence to support either side of this argument I have no interest in either side being correct. Unfortunately it has been derailed as some people are very defensive about the stock exhaust lol.

 

Well, I just purchased the MPx exhaust and a catless dp (no more of my gutted stock cats crap)... maybe I can get some dyno time at the local shop and put up some real tests...?

 

You will definitly feel the catless down pipe. As for the Mpx catback you will be waiting til the end of the month for it to ship like me.

 

Well, I'm no expert on the topic but I know a thing or two at least. Best thing is what's planned - a before / after of the two exhausts.
It's hard to say otherwise and size alone is not enough to go by.

Take our intakes for example and how sensitive the MAF is. The MAF gets skewed because of vortex's being created in the intake and disrupting flow. The same thing can and does happen in the exhaust flow. The crush bent stock bends could create some vortex's that disrupt flow and restrict it. No one knows, no one will until a test is done like the OP plans. He was just asking if a before/after dyno exists.

I remember reading somewhere about fluid flow through a cylinder. It said that as the size doubles, the flow quadruples. Meaning that as an example if you went from a 2" to a 4" that you don't get double the flow - you get quadruple the flow. I can't remember where I saw that but I remember reading about it when studying exhausts for my last car.

 

As size increases, you also lose velocity. Selecting proper exhaust size requires compromise. The stock 2.75 exhaust really isn't as big of a restriction as people think it is. I'm interested to see dyno results, but I'll tell you right now there won't be a huge difference. Also, keep in mind, that area under the curve is more important than peak numbers...

 

The stock exhaust is not "crush bent".

The SS/TC & SS/SC both have mandrel bent catbacks from the factory.

Just read through the thread, and numerous people said the same as me.... Oh well, I'll leave my post up as well.

 

Its not a crush bent. Anyone that says that hasnt looked under there car or paid close attention to it...

 

Are you arguing with yourself Cuda?

 

Since were on the subject of exhaust, anyone have a video clip of a stock exhaust with a diff muffler, lets say a borla or flowmaster? I have a muffler delete buttt I wanna tone it down a bit but still be louder than stock

 

going to a 3" exhaust might not do much other than help with spool up and maybe above 6000rpm in my opinion... it'll deff sound cooler and honestly thats why most people change exhaust anyways.

FWIW, we've made 711whp, spinning 235/60 ET Streets, thru a full 3" exhaust on my friends 2.0L DelSol with a GT4088 on Q16...

 

Donkeyballs is a great example, made JUST under 400whp on the stock cat-back. And it isn't crush bent, look at the photo bpacek (sp?) posted..

 

hahn came out with a new system??? interesting.


Also, I am also on a byt tune putting down 310whp and 360wtrq on the old tables/tune, will find out differences next week when i hit the rollers, and uh, I just have a catless 3in and an intake. Stock catback. I think the sound is awesome, only other exhaust ive ever heard for this car i liked was the hahn. I dont feel as if I am being restricted by it. For the money, id rather get an intercooler.