To stretch my neck way out there with all the recent post on the "best exhaust" for the R56 and such (ps i tried to search using exhaust+cut+out as the search key words and really didn't find what i was looking for if someone knows a trick or a thread that covers my question please point me into the right direction) but i digress. So why not have any exhaust at all? http://www.quicktimeperformance.com/QTEC/index.php
"Dyno Proven Results!
Gains vary from vehicle to vehicle.
30HP gain on a WRX (A turbo car)
20HP on a SRT4 Neon (Another turbo car)
75HP gain on a Turbo Honda (yes another)"
Sure buyer beware on dyno and people just selling stuff to anyone who will buy it but the science is there. Without removing or changing the stock exhaust you do a simple cut out weld up a short pipe (or resonator) so you are not burning up your under belly. When you would like to GO GO GO you flip the switch. (It will probably sound like a MIG taking off but.....) Without having any restriction the exhaust gases should have a quicker escape velocity.....right? (This was covered some what in the 3' vs 2.25' vs 2.5') Someone please talk me out of this before i do something crazy (or just tell me its not really that crazy after all just not so civil)

 

I remember awhile ago someone else did this, long before anyone had developed exhausts for the R56.

My opinion, very ghetto, very risky, very illegal.
Ghetto -- why hack the exhaust off a 20K car, just buy '72 vega, sounds the same.

Risky -- you do realize the exhaust system carries heat away from the engine, and engine bay, there is sure to be repercussions from this, not to mention you may even end up breathing the exhaust.

Illegal -- my state, and town are pretty strict about sound level, hell my ducati with an open resonator and 45mm cans gets pulled over occasionally.

 

1. sounds cool...
2. wouldnt it cause inefficiency when using the stock system w/o the switch?
3. also seems it is prone to leak after a short amt of time.
4. flipping a switch does seem cool tho =]

 

I wouldn't be hacking the exhaust OFF i would just be by passing once and a while. The cutout opens when you want it to so when it was close i would have the stock system in place



Yeah i feel this one i had a pontiac sunfire with a leaky manifold that almost killed me a long time back but that was do to poor maintenance. I would probably lead the cutout gases out of a side pipe and trim up some sort of heat shield. I am not going to just ghetto fab up something



It could be closed most of the time there fore just the stock sound.

 

1yeah i think it would
2 i dont really know i would have to do more research probably have to tune the ecu with it open and closed or something like that. The best likeness would be like having No2.
3 yes most likely but with proper insulation i might get some sort of warranty and the cutout itself would always be replaceable/repairable
4"thats what i was thinking" There was something in a car mag a long time back about a ef civic with the d16 turbo set up and the guy had a cutout. They said it sounded like a diesel truck when it was open but the dyno pulls gave it 25hp with it open. Like i said i think the science is there just need to deside if this is right for me.

 

One of the guys in our club was considering an electrically-operated cutout on his MINI, so when we had a "dyno day", he did a couple of runs with the exhaust in place, then a couple more runs with the exhaust disconnected (I think he disconnected it right after the catalytic converter, since he figured that would be where he'd have the best chance of fitting in the cutout valve.

It didn't make much of a difference at all on the power, and the exhaust sound wasn't all that pleasant with the mufflers totally bypassed, so I don't think he ever went through with it.

 

it seems like it would be the best of both worlds. Could i be in direct contact with your friend? can you get him to pm me?

 

it just that the stock system could be retained. It is all ready efficient and it sounds good. The cut out would and should work. Its would be like having 3" pipe but bigger. I think i am going to go for it. If only one guy on nam knows about it and 2 people of 1000000 say "think about it a bit more" then i am probably just asking the wrong people. thanks for the responses though

 

2 of my friends have this setup. 1 on a new GTO, the butterfly's are right after the headers, and they are electronic; and 1 on a Turbo GN, same placement, but his is manual, not electronic. It's nice to be able to go back and forth.

I say do it!

 

my friend has an 07 corvette z06 - which comes with the butterfly valves in the mufflers. he got headers done and the system goes from headers to (but not including) the mufflers. he has a switch on his and its a HUGE difference in sound and performance (ive driven the car and can attest to it). regardless....i am debating getting that system from QTP for my turbo-back...well see what happens. ill keep you fellas posted.

 

My shop has the zo6 and its not a big deal the car is loud enough already.
And i have a manual one on my gto its just noise i think its fun at times.

 

I had one on my first SRT-4... with a 3" O2 Housing and 3" DP into the cutout it sounded great at the strip with noticably more pull (not just noise!)

Being able to flip it closed with just a switch was also nice in the Chicago suburbs where exhaust laws run hot/cold depending on the week...

 

I actually had this system on my Trans Am with a built engine and the sound is mean and a good diference in power then again you get so much attention from the Cops it's not funny at all.
After a few months of having it it started to leak and later on the motor died so for the amount of money I spent it wasnt worth it.
I also had an SRT-4 and the best way to get sound and power out of it was to replace the cat back with 3" pipes with a resonator and a side exit not all the way to the back and the sound was awesome and you can see it back fire everytime you power shifted.
Now on my MINI I have a Minspeed exhaust it has awesome sound but I wanted more so I cut out the resonator and put a straight pipe but the guy that did the welding didnt do a great job welding it so I'm gonna have to get it re-done.
So to me cut outs are great on V-8's not on small cars like ours.

 

Exhaust cutouts that are properly done bypass the cat or a very restrictive muffler. Here is one I did. It was for a 60 year old gentleman who wanted to open it up when a ricer sat next to him at the light. he would open it up and rev it pretty good.

Im not a fan of cutouts (electronic) because they all leak. You have to put red rtv on the valve often.

 

I agree, this is my grown up car and the last thing i want is to sound like a rolling turd but i really would like more power sometimes. I don't want to use the same forumula that i have used over and over ... Intake, exhaust, ecu....ei. I just wanted to try a different rout

 

What company did you buy from? Were they reputable?

 

If you beat me to it could you pm me with the install proses and the post buyers remorse

 

I've seen the car's run on dyno's with various exhausts and without one *Unbearably loud, and sounded like TOTAL crap*, the car made like 2 HP more without the exhaust.

Cat back's don't really make power, it's all for sound. If you wanna make some power, slap on a downpipe and call it a day. As for the companies claims of 75 HP gains... I don't know what to say there.

I'm skeptical that something like this could produce gains of more than 4-5 HP, maybe 10 HP on a car with an extremely under-engineered exhaust. 75 HP is a bit on the "We were on drugs when we came up with these claims" side though.

I'm not sure how the car would react torque wise. We lost several lb-ft of torque going cat-less on the R53. We've noticed similar trends with other back pressure reduction techniques.

 

FWIW...I took the car for a quick spin when I removed the stock exhaust, with just the open downpipe. It's not nearly as loud as one would think, the turbo really muffles it. It's about as loud as your obnoxious exhaust Nick .

 

I only have an R53 frame of reference, but even full blown race cars run exhausts, very rarely just open pipes.

My car isn't that loud! Your turbo diesel is just quiet...

Stop posting and drive out here already!

 

Have people forgotten the saga of the WMS exhaust already ?

-Brian

 

What was the "saga"?

 

+1

Back to the OP's question. Ignoring the "OMG this idea has already killed you" hype, it's pretty easy to figure out this idea is OK on paper until you bring the specifics of the R56 into play. The downpipe has a close-coupled catalytic converter, and the beginning of the cat-back [where it starts under the oil pan] has another cat and a center resonator before getting halfway back in the car. Doing a cutout that would be the least bit effective means you'd have to do it upstream of the main cat, which means it'd be right at the wastegate housing. If you can squeeze in a servo valve and a 2nd exhaust pipe there, then you definitely deserve to try the idea out. Other than that, my advice would be to get a turbo-back exhaust from ALTA or whatever and be done with the whole shenanigans. MachVDan did a test when he first picked up his R56 and did just a quick dump-pipe off the turbo test and found that it had peak gains of 20wHP and 25wLbFt from the full stock exhaust. This is just a pipe tossing the exhaust to the ground under the engine bay like an old ghetto 60's muscle car. My custom turbo-back system had peak gains of 27wHP and 23wLbFt. The higher peak power gain may be due to the fact I used a tight-radius bend off the turbine housing to improve the transition from radial to laminar flow. The cavieat here is it appears turbo back exhausts can impact the boost controller, actually changing the boost curve and making the car tougher to instigate overboost on command. You win some and you lose some with this current-gen fancy electronics.

Unless you want to build your own system, my advice is again to just buy a good quality turbo-back system that suits your acoustic, volume, and aesthetic needs.

Cheers,
Ryan

 

Ryan to the rescue...

 

Mine has been on since May 2006. Still sounds great. Never did the cutout, though.