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Discussion Starter #1
Y recently installed a 2.5 crush bent exhaust in my car and I rapidly noticed some low end power loss.(by the way my mods are in my signature).

Let me explain what is happening,
I run the car from first gear at almost 1500rpm and floor it and the car revs up very slow(in comparison to before) until it hits almost 5000rpm, then it becames a beast, tire spinning, you know all the goodies.

I know that the cams have to do a lot with this, but it has became very noticeable after the exhaust.
By the way I have a 2.25 WRX OEM muffler to keep it low during daily driving.
But I also have a 2.25 Ultraflo. Im going to install the ultraflo and see what happens.


What you guys think its happening???
 

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no..its not my daddys car
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Storm88000 said:
Well basically you sacrificed some bottom end for top end. Not all that unusual, happened with my car too.
yep yep! youll get used to it! lol
 

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you've made a big mistake what you've needed is a mandrel bent exhaustnot a crush bent,and the optimal diameter on an non turbo 2l is 2.25 not 2.5,but they ve found power on 3 inch exhaust an big cam
 

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PLAY MY HEAD, MONKEY!
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sentra94jwt said:
you've made a big mistake what you've needed is a mandrel bent exhaustnot a crush bent,and the optimal diameter on an non turbo 2l is 2.25 not 2.5,but they ve found power on 3 inch exhaust an big cam
lol, not a big mistake...
 

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The Serbaninator
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sentra94jwt said:
you've made a big mistake what you've needed is a mandrel bent exhaustnot a crush bent,and the optimal diameter on an non turbo 2l is 2.25 not 2.5,but they ve found power on 3 inch exhaust an big cam
I guess you've missed all the breakthroughs lately.....he hasn't made a big mistake. I'll be running 2.5" and probably make some stronger top end with it.
 

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Tired Greasemonkey
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sentra94jwt said:
you've made a big mistake what you've needed is a mandrel bent exhaustnot a crush bent,and the optimal diameter on an non turbo 2l is 2.25 not 2.5,but they ve found power on 3 inch exhaust an big cam
not with cams a 2.5 is much better for cams than a 2.25
 

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Discussion Starter #10 (Edited)
I'm just startin to love my exhaust :D

Last night I just proved that the car is way better with the 2.5.
i raced a friend of mine that has a 200sx SE-R and before installing the 2.5 I ran with him with the 2" and I just pulled one car lenght on him, but last night I pulled over two and a half car lenght.

So the exhaust is just gooood!!!!!! :cool:
 

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I need me SE-R
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worldcrafter said:
yep after installing my exhaust, I noticed mini vans and trucks can keep up with me at low rpms... sucks
What? Just exhaust and it made that much of a difference? Its like max 5hp depending on mods. :confused: Where's the dyno to prove you lost SOO much power?

Classic Zak said:
you lost some back pressure.
Read up buddy. Know before you speak. Loosing back pressure is a good thing. :rolleyes:

sentra94jwt said:
you've made a big mistake what you've needed is a mandrel bent exhaustnot a crush bent,and the optimal diameter on an non turbo 2l is 2.25 not 2.5,but they ve found power on 3 inch exhaust an big cam
Mandrel bent is good. Crush is cheap. It won't make a huge difference.
Unless you have actual dyno proof that a 2.25 with s4's over a 2.5 is actually good...well, you know, shush.
If you don't have cams, you shouldn't go over 2.25. Cams smaller than C3, wouldn't go over 2.5. Built motors going past 170-180whp...3''.
And they didn't perform the dyno on a VE. It was Mike Kojima's built DE motor. He just posted that it would be beneficial to VE owners since 180whp to them is bolt on's and cams.
 

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I need me SE-R
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ralphy SE-R said:
I'm just startin to love my exhaust :D

Last night I just proved that the car is way better with the 2.5.
i raced a friend of mine that has a 200sx SE-R and before installing the 2.5 I ran with him with the 2" and I just pulled one car lenght on him, but last night I pulled over two and a half car lenght.

So the exhaust is just gooood!!!!!! :cool:

:rolleyes: I love when people speak after they tested their butt dyno's. Next time dyno it before and after.
 

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the JWT ECU will get you back some low end and maybe some tuning with cam gears...There are dyno numbas for that stuff.

I wouldn't admit that minivans and trucks keep up with you. I just got a flywheel so I get out of there quicker. It's saved my life a few times on the worst stretch of trucker highway in the world.
 

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Nobody says that 2,5 wont give 1-3 ponnies more up top than 2.25.
But i would prefer to loose 2 top end hp with a 2,25, but gain much more torgue from 1500-5000 , where i drive the car most of the time.
its up to everyone personal taste.
I am reffering to s4 cams, Mikes big motor has many more things plus huge cams.


alex29
 

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SNAIL SQUAD
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Ralphy your car is doing what it is supposed to be doing. My car does the same. Keep in mind when you put the S4's in you lost some low end power. Now you got a bigger exhaust and you lost a little mor elow end power. Now on the high RPM side hold on!!

My car is a pig down low. On the high side get out of my way.

I run 2.5 cruch bend exhaust and my car is far from under powered!! I think at 159.8 whp and 136.4 ft/tq it is pretty damn good :)
 

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SE-Rican said:
Ralphy your car is doing what it is supposed to be doing. My car does the same. Keep in mind when you put the S4's in you lost some low end power. Now you got a bigger exhaust and you lost a little mor elow end power. Now on the high RPM side hold on!!

My car is a pig down low. On the high side get out of my way.

I run 2.5 cruch bend exhaust and my car is far from under powered!! I think at 159.8 whp and 136.4 ft/tq it is pretty damn good :)
awesome numbers! what else do you have on there? What RPM do your peaks occur at?
 

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Discussion Starter #18
SE-Rican said:
Ralphy your car is doing what it is supposed to be doing. My car does the same. Keep in mind when you put the S4's in you lost some low end power. Now you got a bigger exhaust and you lost a little mor elow end power. Now on the high RPM side hold on!!

My car is a pig down low. On the high side get out of my way.

I run 2.5 cruch bend exhaust and my car is far from under powered!! I think at 159.8 whp and 136.4 ft/tq it is pretty damn good :)

Thankss bro!!
Soon I'll be installing the Ultraflo muffler and take it to the track :D
I'm expecting a 14.6 ;)


Peace :rolleyes:
 

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When I swapped in a 2.38" catback, I lost a very noticeable amount of low end with maybe a small gain up top. I custom made my own 1.8" silencer tip for my muffler and gained back most of the low end. I was grinning at the huge amt of torque I got back from a mere silencer. Your ultraflow muffler might reduce your lowend even more if it is of a bigger diameter than the stock wrx. And crushbent really doesnt matter if he's using a 2.5" and it should even improve his low end over a mandrel bent.
 

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Discussion Starter #20
99SE-L said:
When I swapped in a 2.38" catback, I lost a very noticeable amount of low end with maybe a small gain up top. I custom made my own 1.8" silencer tip for my muffler and gained back most of the low end. I was grinning at the huge amt of torque I got back from a mere silencer. Your ultraflow muffler might reduce your lowend even more if it is of a bigger diameter than the stock wrx. And crushbent really doesnt matter if he's using a 2.5" and it should even improve his low end over a mandrel bent.

I know that the ultraflo is going to do that but at the track it really does the job :D
I've already tested it, before installing the cams and the 2.5 exhaust.
15.0 with the ultraflo & 2'' exhaust(this was a bad run, bad clutch)
15.1 Nissan OEM muffler also with the 2'' exhaust and new clutch(OEM)

I also use the WRX muffler for daily drive because it's quite and also gives me some backpressure for those highway runs.
By the way the ultraflo is 2.25 not 2.5.
 
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