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Old 12-03-2004, 09:45 PM
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Default cut out open or closed

i am going to go get my car dynoed tomorrow at speedtek and was wondering if i were to leave the cut out open would i pull more hp than with through the muffler. i have k&n fipk kit,mac mids and carsound cats through a single chamber flowmaster dumped to the ground. my car is 2000 ls1 a4 pretty much just exhaust work. what should my car pull.
Old 12-03-2004, 09:55 PM
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Do a pull w/ it closed and open and u'll see maybe a few hp( jus my 2 cents) Im guessing 320rwhp+ or - with the verter locked. I did 330rwhp on my 99z28 w/ similar mods plus a few more but all dyno's are different. Hope you get the numbers ur hoping for!!
Old 12-03-2004, 09:59 PM
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keep it open! i gained about 5rwhp before H/C
and about 15rwhp after H/C......

KEEP IT OPEN!
Old 12-03-2004, 10:26 PM
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Originally Posted by M6HuggerSS
keep it open! i gained about 5rwhp before H/C
and about 15rwhp after H/C......

KEEP IT OPEN!
Yeah, lots of people gain a good bit leaving them open. Id take M6HuggerSS's advice & run open but if you need to see it with ur own eyes just do a pull open and closed. Im betting u'll see a gain no doubt. I once had em but when i dynoed my SS when it was a H/C car i left em open so i dont have any comparisions of my own. Bet i wouldve lost 10rwhp or so had i done it closed!
Lazy, Are you just makin some pulls or actually getting a tune?
Old 12-04-2004, 10:04 AM
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just pulls for right now.i want to put heads and cam in before i get it tuned...
Old 12-04-2004, 10:13 AM
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Whats the point of a cutout if you're going to leave it closed?
Old 12-09-2004, 07:51 PM
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Originally Posted by SDC
Whats the point of a cutout if you're going to leave it closed?
there you go
Old 12-09-2004, 08:25 PM
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whihc would show more torque or is the backpressure really not that effective?
Old 12-09-2004, 10:15 PM
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I have 3 electric cutouts on my white T/A and ive dynoed open and closed.

keep them open!!
Old 12-10-2004, 01:33 AM
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im sorry but y do u have 3 cutouts.... isnt that overkill ?
Old 12-10-2004, 10:21 AM
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i have 1 on each side of the y-pipe and then one on the i-pipe.

i had the one on the i-pipe first and then just added the other 2 to the y-pipe.
its actually pretty cool to have 3 because i can close the front 2 and only have the back one open so that way its not to loud.
with the front 2 open its LOUD.
one of the guys at qtp has 3 on his also.

i gained 20rwhp by having only the rear one open and then another 15 or so with all 3 open (35)
Old 12-10-2004, 12:15 PM
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Originally Posted by WicketMike
i have 1 on each side of the y-pipe and then one on the i-pipe.

i had the one on the i-pipe first and then just added the other 2 to the y-pipe.
its actually pretty cool to have 3 because i can close the front 2 and only have the back one open so that way its not to loud.
with the front 2 open its LOUD.
one of the guys at qtp has 3 on his also.

i gained 20rwhp by having only the rear one open and then another 15 or so with all 3 open (35)

You gained another 15 rwhp opening the 2 in the y-pipe OVER just one in the I-pipe? That is pretty tough to believe especially considering your car only has 400 hp. Do you have a graph you can post? How was torque affected?

Sorry but until you prove me wrong, the flag is going up.
Old 12-10-2004, 02:55 PM
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Originally Posted by matts22
You gained another 15 rwhp opening the 2 in the y-pipe OVER just one in the I-pipe? That is pretty tough to believe especially considering your car only has 400 hp. Do you have a graph you can post? How was torque affected?

Sorry but until you prove me wrong, the flag is going up.
i actually gained 40 but that was the first time. thet next dyno day it was 35.
my 400rwhp is unlocked also.

go buy some more cutouts and you will see. i do have a graph but noway to post it right now.
Old 12-11-2004, 06:32 AM
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Keep it open. On my 99SS, I gained 8 rwhp/tq when I opened it. On my 94Z28, I gained 15 rwhp. Amazing how the cutout was worth more on the 94 considering I do have a flowmaster cat-back. On the 99 the cat-back is stock.
Old 12-11-2004, 09:03 AM
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I just got done dynoing my car yesterday and this past weekend after getting it back. Leave the cut-outs open, I've still got the stock cat-back on the car with dual cut-outs at the collectors I gained 28 rwhp & 32 rwtq at the wheels when I opened them they work. But leave it closed for the first pull then un-cap and see what you put down.
Old 12-11-2004, 11:50 AM
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I gained 18 rwhp and 10 lbs of tq with cutout over edelbrock catback. Now I just added the fm13 cam and when I get it tuned I will make a pull with the muffler to see if it changes
Old 12-11-2004, 12:04 PM
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Originally Posted by WicketMike
i actually gained 40 but that was the first time. thet next dyno day it was 35.
my 400rwhp is unlocked also.

go buy some more cutouts and you will see. i do have a graph but noway to post it right now.
I never said that gaining 35 from cutouts wasn't possible. Not probable but possible. I just have a hard time believing that you gained 15 rwhp with 2 cutouts in the y-pipe OVER 1 cutout in the I-pipe. Maybe if you replaced restricting cats in the y-pipe, MAYBE I would believe it. But if you just put the cutouts in open pipe, that's pretty far fetched. Explain or find a way to post up the graphs.
Old 12-11-2004, 05:20 PM
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Originally Posted by matts22
I never said that gaining 35 from cutouts wasn't possible. Not probable but possible. I just have a hard time believing that you gained 15 rwhp with 2 cutouts in the y-pipe OVER 1 cutout in the I-pipe. Maybe if you replaced restricting cats in the y-pipe, MAYBE I would believe it. But if you just put the cutouts in open pipe, that's pretty far fetched. Explain or find a way to post up the graphs.

i dont have cats.

the cutouts on the y-pipe are right after the headers. its almost like having open headers. i still have stock muffler but the cutout on the i-pipe is before it of course. ive had the car dynoed about 20 pulls and same results everytime.




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