Orange Juice

iTrader: (3)

Rampant and I have talked about this in the past. It shouldn't be an issue with HP tuners switching to a "cutout" tune from a street tune. I'm have a single 4" manual cutout which comes off an 10" extension that is after my flow master merge.

RAMPANT

iTrader: (17)

It does not stop me from trying to educate those, young and old of my hard learned mistakes.

Did I just call you old? :-)

RAMPANT

iTrader: (17)

As Orange Juice said, if you do not mind switching with HP Tuners you can do that. I recall some one made a dual ECU deal that was switchable, but do not know if they built it or not, or if it worked.

Jadedbird

iTrader: (27)

Frost offers one. I might check into that and the hptuner

moeZ28

iTrader: (7)

I dynoed the same with closed cutouts as I did with no cutouts...no turbulence problems there...Your CATS cost you more than 8rwhp...If they didnt, more people would run them and not care about the performance loss.

Camaro Z

iTrader: (5)

Mine gained 10 rwhp 10rwtq back to back. This was when my car had bolt-ons only with pacesetter headers, ORY, flowmaster muffler, and a 3.5" cut-out

RAMPANT

iTrader: (17)

Reread the posts, they did not!

It made 511 with them, 519 with out. It went 11.0@129 thru Cats. The 478 was thru cats cut outs closed, 511 was cutouts open thru cats. The 512 was thru the full Magnaflo no cats. All pulls 1 day apart same dyno and tuner.

As for the guy picking up over a Flowmaster, the are known to be terrible cat backs.



I have some real special ones on the car now. Hoping to see over 600 rwhp with cats and passing Canadian emissions. We will see how that goes in a week or two. They are OBDII certified too. Not cheap though.

3 1/2" inlet, 4 1/2" OD.

Troy5061

iTrader: (19)

Same track, within the same week with about the same weather conditions 90 degrees and humid. They were both on 295/50R16 M/T ET Street DRs. 3 runs with each setup and they were all about the same mph with each setup.

btw, it's a manual cutout, I only use it at the track and I just take the cover off when I put my ET Streets on. I probably wouldn't have bothered with a cutout if I had a good high flow catback but it was easier to spend $32.99 on the cutout vs $400 on a magnaflow kit with tips I dont like. Plus it just sounds cool!!!

Jadedbird

iTrader: (27)

so some people it hurts... and other people prosper...

from what it looks like... its more of a tuning issue... and the bigger the power(bigger CI or FI or N02), the more benefitial the cutouts are...

is anyone else picking up on this pattern?

RAMPANT

iTrader: (17)

Where do you see that trend, I made 512rwhp through full exhaust, no cut outs and 519rwhp with open headers. Has anyone else that commented made more than 500rwhp? It was my 412ci LS2.

The 478 was purely turbulence from the cut outs. All the power came back when we opened them. No extra power though. Not sure where people are getting lost on this.

I see people with crappy Y pipes and cat back (especially restrictive mufflers, like a Flowmaster) are picking up more power and have little more than stock bolt on motors.

That said, I do think you can gain 10ish rwhp, I just prefer to always have it all on tap all the time. Maybe that is just me.

Jadedbird

iTrader: (27)

ive been searching throughout this forum, tuning forums, and ls1lt1 and that seems to be the trend

lol i get slammed for not searching and then i get slammed for searching... i just cant win! haha

stumprrp

iTrader: (2)

12:1 396 LT1

Dual 3" open cutouts after the headers - 414 RWHP
Decent y pipe and a 3" dynomax ultraflow - 400 RWHP

torque curve beefed up, but that dynomax muffler was a good piece!

Jadedbird

iTrader: (27)

were they cutouts capped in the 400 pull or were they not even on the car then>?

stumprrp

iTrader: (2)

Capped.

I also had a single 3" cutout setup with a magnaflow out back, different dyno, that was 410 RWHP single cutout open, 390 RWHP cutout closed through the muffler. No clue what my true duals made after that.

I think a dual exhaust or even a single 3.5 using a dynomax ultraflow or hooker maxflow would be the perfect system.

thunderstruck507

iTrader: (18)

My car has duals (no crossover) with dual cutouts 12" behind the collectors.

Back when I had 2.25" exhaust over the axle the cutouts were worth 2 tenths and 1.5-2mph in the 1/8th mile.

Once I had 3" exhaust from cutouts to mufflers with 2.25" tails they still gained a tenth and 1 mph.

Once I had 3" from cutouts to mufflers (except a shitty joint right at the collector which was still 2.25" and entered the 3" pipe at a 45* angle) with 3" dumps after the muffler they gained little to nothing.


Since then I have corrected the joint in front of the cutouts. My exhaust guy couldn't make a tight 3" bend so I was stuck handicapping it with a 3" to 2.25" reducer welded at an angle into some 3" pipe at the collectors. This meant the exhaust left the header into an extreme bend necked down to 2.25" for a length of 2" then into 3" to a cutout to 3".

I'm curious to go back and see if I gained anything losing the 2.25" and if the cutout might start helping again since now the mufflers are a bigger restriction than the shitty joint at the collector. I know for a fact it drives a lot different in the low-mid range with a proper 3" setup all the way back.

Troy5061

iTrader: (19)

It obviously depends on the setup as every car is different. I could care less about dyno numbers, the proof is in the pudding with track results, I gained almost 2 mph in the 1/8th because my stock cat back piping and dynomax muffler are restrictive. If you have a better flowing exhaust the less the gains will be

82cetuner

iTrader: (9)

My car gained a total of 20RWHP and 19RWTQ on back to back dynos with the cutout closed then open, I had the car tuned with the cutout open. I am sure alot of my loss comes from the single 3 inch catback after the 4 inch cutout and y pipe. my motor makes way to much power and to big of cubes for a single 3 inch to not lose anything. im sure if I had a good tru duel setup the loss would not of been as great but for now i noticed a difference in how it runs with it open vs closed. I also dont see how anything could be damaged by a exhaust that is a bit restrivie or un restrictive, after all how many people actually get tunes after going to a different exhaust with no cats and a catback?

Blk98Vert

iTrader: (2)

OP my point is that unless you are running a big muffler with multiple chambers or a turbo muffler there is no point to adding cutouts on a true dual setup. With a muffler like an XR1 or a Magnaflow they are straightthrough mufflers, so you are bypassing something that has no more restriction than an open section of pipe. I can understand running a quiet muffler like a full size Borla or Magnaflow and using the cutouts to make it loud when you want to but there would be nothing to be gained by running them. Does that make sense?

Jadedbird

iTrader: (27)

Yeah i understand. But if (and when) i go to d1sc or even f1a, its best to get the exhaust out asap because the procharger so throwing so much air down its throat.

It seems like anything with big power needs a good air intake and a good exhaust out take.. And what with dual 3" cutouts after the headers, you cant get much better flow than that haha.

But troy said a few posts above.. I looks like it does depend on the setup.
Cutouts may be overkill right now, but for future expansion, it looks like they would benefit me.

Blk98Vert

iTrader: (2)

What I am trying to say is that it wont matter, you would be bypassing a straight section of pipe. If you want it for sound do it but it wont gain, as stated you have nothing to bypass unless you are running a full size chambered muffler