2.5" NPP vs. 3" cat back with TT???

['14-ELLIE]

Hey guys,

I've searched a bit, found some good info, but not quite the exact answer(s) I'm looking for. Right now, my 1LE is getting TT's installed and my plan was to install the SW 3" ZL1 cat-back (CA12CB-FMT). The FMT version has resonators at the x-pipe but not in the rear exit. Love the sound of the SW and figured going 3" would help with flow = a bit more ponies.

Well, the exhaust came in today and it's the wrong one! (CA12CB with resonators in the x-pipe and rear). With the build happening now, I have three options:

1. Wait for the right exhaust to get here, holding up the build...
2. Getting a different 3" that is readily available (really want to keep the quad tips)...
3. Or save the money and keep my NPP installed

I guess my main question is what I'm looking at in power difference with NPP vs a 3"? Already going with JBA cat deletes, ZL1 with BAP, 90lb injectors, and meth.

Thanks for any help!

[racesloth]

Stick with a 3" exhaust turbos need to have an unrestricted exhaust the bigger the better. My drag radial car is large frame single 88mm which starts out with a 5" down pipe and then necks down to a single 4" pipe before dumping at the rear axle...

[Unreal]

Kit you ordered is 2.5 inch downpipes so wont make much of a difference. on a kit with 3 inch downpipes 40-60 hp has been seen with a good full 3 inch exhaust.

[Ajdin@A2BMotorsport]

Originally Posted by '14-ELLIE

Hey guys,

I've searched a bit, found some good info, but not quite the exact answer(s) I'm looking for. Right now, my 1LE is getting TT's installed and my plan was to install the SW 3" ZL1 cat-back (CA12CB-FMT). The FMT version has resonators at the x-pipe but not in the rear exit. Love the sound of the SW and figured going 3" would help with flow = a bit more ponies.

Well, the exhaust came in today and it's the wrong one! (CA12CB with resonators in the x-pipe and rear). With the build happening now, I have three options:

1. Wait for the right exhaust to get here, holding up the build...
2. Getting a different 3" that is readily available (really want to keep the quad tips)...
3. Or save the money and keep my NPP installed

I guess my main question is what I'm looking at in power difference with NPP vs a 3"? Already going with JBA cat deletes, ZL1 with BAP, 90lb injectors, and meth.

Thanks for any help!

Stick with the NPP setup with fuses pulled, the main thing with turbo cars is to keep back pressure as low as possible. Im running a 3" DP to a stock 2.5" Catback with Muffler Deletes on my car and that will be enough, our shop LSx Turbo 02 Z/28 (but who really knows when it will be done) will be running a single 88mm to a 5" DP to 4" pipe probably similar to racesloths probably.

Restriction and Backpressure are killers on turbo cars.

['14-ELLIE]

Went with the 3" ZL1 Corsa. Car will be on the dyno today. We'll see how she does!

[cabbe]

How much do you want for your old npp?

[Fraxum]

I went from NPP to full 3" with a modified Magnaflow ZL1 (quad-tip) catback. AGP told me the main benefit is the turbos will spool a little sooner with the 3". I think you only get any noticeable HP gains if you are making big power. My guess 800+?

I am at 600+. I was hoping for a better 60' but so far it has not happened. Other changes to my car have conspired against me and maybe I have too much tire.

I will say with my windows open I hear the whistle a little sooner.

As to sound it is much deeper than my NPP and only a little louder than my NPP. And there is a little drone. But, my NPP has a Magnaflow xpipe muffler. I put that on there when I had LTs, as I hated that sound. Of course with the AGP kit the LTs are off.

I am getting used too the slightly boomy, raspy sound and kind of like it. But I do miss the NPP flaps closed for quiet cruising.

My vote would be save your $$ for now and mess around with the exhaust later. Probably this is too late.....

['14-ELLIE]

Originally Posted by Fraxum

I went from NPP to full 3" with a modified Magnaflow ZL1 (quad-tip) catback. AGP told me the main benefit is the turbos will spool a little sooner with the 3". I think you only get any noticeable HP gains if you are making big power. My guess 800+?

I am at 600+. I was hoping for a better 60' but so far it has not happened. Other changes to my car have conspired against me and maybe I have too much tire.

I will say with my windows open I hear the whistle a little sooner.

As to sound it is much deeper than my NPP and only a little louder than my NPP. And there is a little drone. But, my NPP has a Magnaflow xpipe muffler. I put that on there when I had LTs, as I hated that sound. Of course with the AGP kit the LTs are off.

I am getting used too the slightly boomy, raspy sound and kind of like it. But I do miss the NPP flaps closed for quiet cruising.

My vote would be save your $$ for now and mess around with the exhaust later. Probably this is too late.....

You're right, it is too late! haha. I do see the benefit of 3" though. If you're going twin turbos, it seems really counteractive not to increase the flow. I went ZL1 Corsa and am very happy with it. It isn't too loud at cruising (I had the NPP before), even with the cats now gone. I'm at 660RWHP right now and plans to be somewhere in the 750 neighborhood in a month or so.

[Fraxum]

Originally Posted by '14-ELLIE

You're right, it is too late! haha. I do see the benefit of 3" though. If you're going twin turbos, it seems really counteractive not to increase the flow. I went ZL1 Corsa and am very happy with it. It isn't too loud at cruising (I had the NPP before), even with the cats now gone. I'm at 660RWHP right now and plans to be somewhere in the 750 neighborhood in a month or so.

Did you get the 2.5 " section cut out to be 3" all the way?

['14-ELLIE]

section??

Turbo downpipes to JBA 2.5" catless midpipe to 3" ZL1 Corsa. So, 3" from cat (or catless) back.

[Unreal]

AGP runs 3" downpipes and they are offered neck'd down to 2.5" to bolt to factory system or full 3". He is talking about the small 3-4" section of 2.5" if you get the setup for factory bolt on without a 3" system. The Hellion top mount system is 2.5" downpipes, so totally different setup. As long as the pipes are kept the same or bigger no issue. Just don't neck down and it won't effect power drastically.

['14-ELLIE]

Originally Posted by Unreal

AGP runs 3" downpipes and they are offered neck'd down to 2.5" to bolt to factory system or full 3". He is talking about the small 3-4" section of 2.5" if you get the setup for factory bolt on without a 3" system. The Hellion top mount system is 2.5" downpipes, so totally different setup. As long as the pipes are kept the same or bigger no issue. Just don't neck down and it won't effect power drastically.

Ahh, understood. Thanks for the clarification!

[Fraxum]

Originally Posted by Unreal

AGP runs 3" downpipes and they are offered neck'd down to 2.5" to bolt to factory system or full 3". He is talking about the small 3-4" section of 2.5" if you get the setup for factory bolt on without a 3" system. The Hellion top mount system is 2.5" downpipes, so totally different setup. As long as the pipes are kept the same or bigger no issue. Just don't neck down and it won't effect power drastically.

Thanks for clearing that up Nick. My AGP is 3" all way. Love it. But all turbos are fun and interesting. Nice to get thumbs up from Hondas with slicks on the front.