I am wondering what the majority of people think.. This is for a 97 se-rwith a pr cai, 91intake cam, and 19* timing.. I know the greddy is a 2.3XX" and I have seen people saying they feel they could gain a little bit more topend from a little bit larger exhaust. I also got this interesting fact from another foum member:

Here is a chart from a company called Donaldson in Australia that has experience with making exhaust systems for turbo trucks.
Based on 2psi of backpressure, using a gasoline engine, (four stroke). Numbers on the left coincide with your horsepower figures and the right represent reccommended sizing for exhaust:
100.5HP/2" (51mm) diameter
160.8HP/2.5" (64mm)
221.1HP/3" (76mm)
308.2HP/3.5" (89mm)
502.5HP/4" (102mm)

I believe the power rating is coming from the Crank HP rather than the WHP. The source is 21st Centruy Performance by Julian Edgar.

Looking at that chart a 2.5" would be almost perfect for the mods I have and are getting ready for (pullies,header, etc.) Let me know what you all think.. Any input or experiences is much appreciated.

:confused: :eek: I dont know man. i was always bent on a 2.5" exhaust for a built NA VE. accoring to that chart, i would need between 3 and 3.5" exhaust fior a built ve-lets say 230-240 crank HP. thats insane

2.25 or 2.375 should be fine. You actually do need some back pressure. I ran a ghetto 2.25 crush bent and dyno'd at 141.3 on a US motor. Stay away from 2.5 unless you are going VE or Turbo under 300hp.

from all that i've read, the general consensus seems to suggest 2.25". sounds like it's been tried and trued. not sure what to tell you ***.

2.5" is good for me. I ran a 14.5 @ 91mph and all I had done was a 2.5" custom exhaust, PR CAI, Hotshot Header, & NT555r's on a 91 Se-r Motor.
i love my 2.5" exhaust...
http://www.imagestation.com/picture/sraid28/paa86e749edc00d869bf98ad7f4d241d7/fd6a0a46.jpg
:D

I was thinking of using 2.5" piping because of the s4 cams I'm using.
98sr20ve gained hp all across the board with his 2.5" exhaust and suggested i try the same size.

I'm loving my 2.5". You definately feel the gain up top with the cams and other bolt on's. 2.5" is a must if you plan on squeezing.

I was shocked to compare the 2.5 to my stock. Food for thought. My VE with the cams not engaged puts out about 140whp if left to spin to redline. Doesn't this sound just like a modded DE. Does to me. My cams dont enage until 4300 and 5000 rpm. So when I say I lost no power on my VE then I can say with confidence that under 4300rpm my car still benifted from the 2.5 inch exhaust and that a modded DE should behave similiarly. I wish I could post my dyno. Maybe I will try and get a PDF version of it. After that it would seem to be pure gravy on a de as well. Thats my logic. BTW the greddy is 2.38. That would be a good comprimize if you ask me. The 2.5 inch is going to be loud. Mine makes this cool afterfire when I let off the gas after gunning it in gear and shutting down at 4000rpm or so. Just like my old 510 I love it.

[QUOTE]Originally posted by DaGenesis
[B]I was thinking of using 2.5" piping because of the s4 cams I'm using.



My crush bent 2.25" should be rusting out anytime soon and i think im going to go 2.5" also. I figure a fully bolted up SE-R with cams would benefit from a bigger exhaust. didnt Shell from AZ have a Dyno with his Borla and then with his courtesy 2.5"? Hmm, i may have to do some searching

Originally posted by Rob
[QUOTE]Originally posted by DaGenesis
[B]I was thinking of using 2.5" piping because of the s4 cams I'm using.



My crush bent 2.25" should be rusting out anytime soon and i think im going to go 2.5" also. I figure a fully bolted up SE-R with cams would benefit from a bigger exhaust. didnt Shell from AZ have a Dyno with his Borla and then with his courtesy 2.5"? Hmm, i may have to do some searching

IIRC the courtesy is also 2.38/60mm. It is made overseas as most 60 mm exhaust are.

Originally posted by 98sr20ve


IIRC the courtesy is also 2.38/60mm. It is made overseas as most 60 mm exhaust are.

really? i always thought it was 2.5". Hmm..now i have to start searchin!

here ya go......

http://www.se-r.net/header_exhaust/courtesy_exhaust.html

Originally posted by 98sr20ve


IIRC the courtesy is also 2.38/60mm. It is made overseas as most 60 mm exhaust are.

same with HKS, 60mm. Now I'm stuck with a dillema; go with HKS and keep it quiet and sleepy, or custom size it to 2.5" with "whatever" muffler and wake up the neighbors at 3 o'clock in the morning? what you guys think?

Originally posted by metro_se-r


same with HKS, 60mm. Now I'm stuck with a dillema; go with HKS and keep it quiet and sleepy, or custom size it to 2.5" with "whatever" muffler and wake up the neighbors at 3 o'clock in the morning? what you guys think?

Ummm if you have the money go with the HKS of course. I have a 2.5" crush bent (which I've heard equates to a 2.25" mandrel bent) with a "whatever" muffler and no resonator. Loud as f*ck but I dont mind that much.... its not the crappy Honduh civic loud but a more aggressive loud. But yea if I had the money I'd just buy the HKS.

Nice sig pic metro se-r

Originally posted by sentra532


Ummm if you have the money go with the HKS of course. I have a 2.5" crush bent (which I've heard equates to a 2.25" mandrel bent) with a "whatever" muffler and no resonator. Loud as f*ck but I dont mind that much.... its not the crappy Honduh civic loud but a more aggressive loud. But yea if I had the money I'd just buy the HKS.

No resonator will be very loud. I needed earplugs to drive mine like that. I put a Dynomax Bullet on there and it really helped. If I had been patient I would have ordered the Magnaflow that is a little longer and has more packing inside the pipe. I dynoed at 171 in richmond with out a resonator and 171 in Virginia Beach with a resonator. I guess it didn't hurt me and both the dyno's were the same basic type. My car does not wake anyone up but my wife can hear the car as I pull into my house from about 50 yards. It is real suttle but she can still hear it. Not nearly as load as half the trucks I hear delivering stuff.

Rob. I could have sworn that Brain at couertesy nissan told me it was a 60 mm. I wonder if it has changed. I have also heard the Couertesy exhaust is drony. Probably like mine. People on a local forum have commented about how good mine sounds. I know I am partial but it sounds totally bad a$$ if you ask me. My wife says she wouldn't change a thing. She is so cool.

Edit: I know it vanity but I latter dynoed at 180whp. Daxxx I cant help saying that.

I have a crush bent 2.5 inch exhaust with a magflo resonator to a Magnaflo Permormance muffler. I had S3 cams, JWT ECU, Stillen Throttlebody, G3 Hotshot headers and ran a 14.7 @ 94 mph ;) Not bad.
I thought that the car benifited from this size with the cams because the car would haul on the highway (Ooops did I say that!)
I will sell it to one of you guys if you want it. I'm putting a 3 inch mandrel bend on as soon as Louis gets me my parts. PM me if interested. I have a 96 (B14), 200 sx.

Originally posted by 98sr20ve


Rob. I could have sworn that Brain at couertesy nissan told me it was a 60 mm. I wonder if it has changed. I have also heard the Couertesy exhaust is drony.

Drony is exactly why I didn't get a resonator. My car is LOUD when I floor it but pretty much silent when cruising at a constant speed. My brother had a 240SX with a resonator which constantly droned on the highway - nastiest sound in the world. He's turbo now and it's so much quieter...except for that awesome turbo sound!

Oops looks like I quoted wrong.. meant to quote 98sr20ve

Originally posted by sentra532


Drony is exactly why I didn't get a resonator. My car is LOUD when I floor it but pretty much silent when cruising at a constant speed. My brother had a 240SX with a resonator which constantly droned on the highway - nastiest sound in the world. He's turbo now and it's so much quieter...except for that awesome turbo sound!

It was much worse without the resonator for me. YMMV