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      12-13-2011, 03:13 PM   #1
fmagz91
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Cat delete power loss??

A month ago i installed ar catless dps which was a pain in the ass.. but worth the power gains.. yesterday i got bored and went to my local welder and took the 2 remaining cats out assuming better flow=more power.. i still got the stock muffler and resi... So bottom line i almost feel like i lost power by deleting the last 2 cats. is this possible or am i just crazy?
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      12-13-2011, 03:20 PM   #2
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Originally Posted by fmagz91 View Post
A month ago i installed ar catless dps which was a pain in the ass.. but worth the power gains.. yesterday i got bored and went to my local welder and took the 2 remaining cats out assuming better flow=more power.. i still got the stock muffler and resi... So bottom line i almost feel like i lost power by deleting the last 2 cats. is this possible or am i just crazy?
You're crazy. You do not lose power from reducing backpressure in a turbocharged system.

Neil
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      12-13-2011, 03:48 PM   #3
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Did the muffler shop use the same OE size dia pipes? Or maybe smaler ones? It might be better to just get a N55 mid pipe. ?
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      12-13-2011, 03:55 PM   #4
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Neil is correct ^^^ I was wondering the same until I did some research, Downstream of the turbine you want the least backpressure possible. The general rule of larger is better of turboback exhausts is true. If you minimize the pressure downstream of the turbine you will make the most effective use of the pressure that is being generated upstream of the turbine.
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      12-13-2011, 04:55 PM   #5
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You're crazy. You do not lose power from reducing backpressure in a turbocharged system.

Neil
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      12-13-2011, 05:10 PM   #6
fmagz91
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guys, im not soo much of a noob, know how it works which is why i mentioned "assumed" in the post.. if i could run open dps i would! but i was asking this for people who know more than me about the n54 exhaust sys.. they are the same size pipes i was watching him weld.. my theory was that since theres so much flow the stock muffler cant handle it on a high map and it backs it up resulting in a power loss.. i noticed good gains on the stock map vs with the cats on the stock map but when i switched it up to high boost i was almost dissapointed.. im going to do some more runs soon and doube check.. my car likes to choose the days she wants to perform so.. and using the n55 dp would be interesting, id like to look into the sizes and such.. but thanks for the feedback guys
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      12-13-2011, 05:11 PM   #7
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midpipe**
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      12-14-2011, 03:46 AM   #8
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You might 'feel' a loss of low-end torque, but the high-end horsepower will sure be there.
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      12-14-2011, 08:27 AM   #9
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... my car likes to choose the days she wants to perform so.. and using the n55 dp would be interesting, id like to look into the sizes and such.. but thanks for the feedback guys
I just measured my N55 mid pipes. The O.D. is 58mm to 60mm depending on where you measure. Maybe you can measure your custom mids.
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      12-15-2011, 02:53 AM   #10
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ahh, i did some more runs today.. its just not the same.. its deff slower on higher boost levels. i'm just gunna get rid of that muffler
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      12-15-2011, 01:57 PM   #11
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I definitely gained power by deleting the 2ary cats and the resonator from the mid pipe. Disclaimer... it was on the 135, the M mods are still pending
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      12-19-2011, 09:52 PM   #12
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I definitely gained power by deleting the 2ary cats and the resonator from the mid pipe. Disclaimer... it was on the 135, the M mods are still pending
yea, you might have gained some power but i did it the wrong way.. wen i first did the dps with cat deletes and the rest stock it was perfect.. i got bored and took the mid pipe cats out and it was too much flow for the stock muffler which robbed me of power on higher boost levels.. now i fixed the solution= straight pipes with a resi.. sounds ridiculously loud when cold but its not so bad once its warm.. and the gains are crazy..
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      12-19-2011, 10:07 PM   #13
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i swap my midpipes with resonated midpipes and my butt dyno says it has gain power.
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      12-24-2011, 07:42 PM   #14
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i swap my midpipes with resonated midpipes and my butt dyno says it has gain power.
nice car btw, and your stock mids, were they catted and resonated to begin with?
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      12-24-2011, 11:04 PM   #15
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nice car btw, and your stock mids, were they catted and resonated to begin with?
Yeah they are, n54 midpipes have cats and resonator.
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