Yea, I searched "cutout placement", etc...I'm sure it's been discussed but if I look anymore it would defeat the purpose of a message board.

With my LT headers, would it be best to get 2 cutouts in the y-pipe, or one where the exhaust comes together in the I-pipe? Besides noise/fumes, are there and problems like if you were running open headers (inhaling air, O2 readings, etc)?

Any tips in general appreciated - thanks!

 

Cut outs will do practically nothing if you dont have cats. You will lose torque down low, can damamge your exhaust valves, and will kill hp up top with knock retard. I ran with open headers and an open y pipe and now with true duals. The true duals by far added the most power. You WILL get false knock from the two cut outs, you dont need two, and open headers sounds like crap. I used to have a Flowmaster 80 series and i liked it 2nd best to my side pipes

 

if you have 2 cats in the y-pipe then you will prob see the most gains with one in front of each. if you have a single cat you can prob just run one right infront of it but may still see better gains from one behind each header. if i ever stop being a poor college student i will get two elec cutouts one behind each longtube

 

Most people that ARE running ORY's are getting MORE hp........

You won't sacrifice low end torque unless you put it too close to the headers as well...Having the cutout too close to the over axle pipe is pointless, it defeats the whole purpose of having one.

You won't get knock retard, and it won't make you lose HP.....Put it where the I pipe and the Y pipe meet right under the passenger side door and you'll be fine. You must have had a BAD placement for it. ALL the cutout dyno's and results I have seen are very positive. How does it not do much..? It's bypassing the mandrel bends that go from the cat back out and making you gain HP if applied right. here....

 

He wants to put two though. I got ALOT of knock retard with open headers. I am assuming he doesnt have cats in his headers so it wont create enough back pressure and could damage his exhaust valves. Not too common but it can happen. Unless you have an LT4 knock module you'll see knock. I got knock retard with my open y pipe and stock manifolds, and i got knock retard with my open headers. I finally got knock tuned out when i put my side pipes on.

 

Overall, replies seem negative toward the cutouts. If so bad, why are so many people running open dual cutouts - open headers even (basically the same, I know...but there is a little more pipe)? Also, why have I seen nothing but gains in freinds dyno results with dual cutouts, not far back from the LTs?

False knock may be a problem, but while I had to drive 30 mins open headers to get a Y-pipe made for me, I experienced none. Im not saying I wont, but Im saying that that was under normal driving conditions...I dont plan to race around town open headers - which brings me to another point. I do NOT plan to drive like this everyday. There are just some times I'd like to hear open headers, and idle past ricers. This will not be a daily thing, not even a weekend thing.

After driving with a cutout on my old setup for a year, I miss the sound in the car and not being able to carry on a conversation with the person next to you.

 

Well you seem like you want them which is the important thing. With the open Y pipe I got false knock about 90% of the time time i raced. You can just feel the top end dying. With opean headers all of the time above 3,000rpm i could feel the power band just dying.

At idle LTs are alot quieter than stock manifolds but they are definately louder at WOT.

 

"Having the cutout too close to the over axle pipe is pointless, it defeats the whole purpose of having one"

why is that?

if the cutout is closer to the the Ypipe...a whooping 2ft...and it is only straight pipe between them...how can that affect power? there is a spot just before the axle that fits the cutout perfectly. IMO the best place to put it.

open headers or dual cutouts can cause alot of false knock due to the reverberation of the exhaust between the ground and the car. on a stock or mildly modded car...dual cutouts won't be much of a gain over the single. now if you were talking a 500hp engine...yeah maybe. but we're not.

just do the single cutout right before the axle and you'll never regret it....unless you get pulled over

 

or unless you have a cat. Don't put the cutout after the cat. It will be quieter and you wont gain as much power from it. Do put your cutout ats far back as possible though. I even tested this with my exhaust. Cut off the flowmaster 80 i had, left the pipe there and it was almost as loud as my true duals at idle. I removed the pipe at the cat and it was still louder, some top end power loss. My cat clogged so i cut it off and it was insanely loud and caused alot of false knock. When i put headers on the headers were alot quieter at idle, but the LTs were alot louder above 1,000rpm and caused alot more knock.

 

Shawn this is the 4th or so thread in the past few day where you said that you could damage exhaust valves due to lack of back pressure, I just figured that I would correct this statement, the damage to exhaust valves with open headers has to do with cool air getting into them whan the vehicle is shutoff shortly after a hot run, and that sometimes warps the valve. also with LT headers this is very uncommon, mids and shorties on the other hand is when you need to worry about that...

also if the cutouts are installed properly witha slighly downward angle then he shouldn't get the knock retard you saw.. think about it the LT's are poining straight back and in a lot of case poit right at the tranny crossmember, causing a lot of extra vibration and that is what causes a lot of the false knock when running open headers...

 

FWIW, I picked up a dyno-proven 15rwhp with the cut-out placed just in front of the over-the-axle-pipe and through the cat.

 

OH yeah I forgot to mention that is where mine is too!

 

Yeah i had heard from several people open headers could damage the valves, but no one really speculated as to why. It does make sense though that if he did angle the cut outs down and out it would cause less resonance. If he aimed them directly down i think it would be louder then because of it reverberating off of the pavement. $260 for a dual electric cut out kit is still alot IMO. For that price you could make a set of GMMG true duals and side pipes LOL.

 

OK, it's pretty clear people agree just before the axle bend is the best place - which is where I had it on my old setup. But what about sound? Reminder: I don't plan on racing with open headers, or driving around daily. Thanks!

 

sound.....


it'll be LOUD