Acura RSX, ILX and Honda EP3 Forum banner

How to tell when I should run bigger exhaust piping

9K views 79 replies 16 participants last post by  all<dc5 
#1 · (Edited)
My current mods are:

AEM V2
Megan Racing Race Header
Skunk2 60mm cat-back

I'm wanting to upgrade my Skunk2 60mm cat-back to the 70mm piping but with my current mods will that be ok or will I end up losing HP because of the back pressure issue?

I have no intentions on a turbo for my whip so the only mods that will affect this are what is listed.

What is the main difference between the 60 and 70mm piping sound wise? Is the 70mm louder or deeper?

I guess what I'm trying to say is that I want my car to sound louder but I like the sound of Skunk2 so will the 70mm be louder than the 60mm?
 
#2 ·
My current mods are:

AEM V2
Megan Racing Race Header
Skunk2 60mm cat-back

I'm wanting to upgrade my Skunk2 60mm cat-back to the 70mm piping but with my current mods will that be ok or will I end up losing HP because of the back pressure issue?

I have no intentions on a turbo for my whip so the only mods that will affect this are what is listed.

What is the main difference between the 60 and 70mm piping sound wise? Is the 70mm louder or deeper?
60mm is the stock size. When i was looking to buy an exhaust i was told time and time again (and you can look it up) 3" piping will give you more bang for your buck, regardless of if you plan on running a s/c or turbo. 3" on n/a motors have been dyno proven to push out more power. Anywhere between where you're at, up to 3" will for sure give you more power. 3" just put out more noise but who cares :thumbsup:

and yeah, bigger the pipe the louder it will be.
 
#5 ·
no, but base models were manufactured to lean towards more as an economical car, as the type-s a performance car. but i've seen some pretty ignorant 5-speed boosted base models. but if you're already running all the mods you have i take it it's not an automatic. go for it.
 
#7 ·
still get a 3 inch exhaust. will net you the best gains either way
 
#8 ·
Well, the MegaPower RR is Skunk2's 3" exhaust but for some reason they went with a 2 flange that bolts up to the cat so my race header has the 3 bolt flange so I can't get it :(
 
#10 ·
They won't touch it because I don't have a cat, my race header has a 3 bolt flange and the start of the catback I want (76mm skunk2) has a 2 bolt flange.
 
#16 · (Edited)
how bout you buy kteller 3" piping, your choice of muffler and res (if you wanna run a res) and have them weld it all together with a flange you can run to your rh and just put the custom cat back on yourself. that way they're not touching the car at all. just welding the exhaust together. i'm sure you can also just buy a flange to match your rh. they won't even need the car at all. just piping, flange, res, muffler, and once it's all welded you just unbolt your current catback and BOOM. 3" custom catback exhaust.
 
#17 ·
how bout you buy kteller 3" piping, your choice of muffler and res (if you wanna run a res) and have them weld it all together with a flange you can run to your rh and just put the custom cat back on yourself.
I might just have to find a local exhaust shop that will do custom work. I could buy the 3" piping and just buy the Skunk2 RR muffler and have them weld them together and see if they could make something work with my flange problem.

Good suggestion :thumbsup:
 
#21 ·
My 70mm skunk2 exhaust is also a 2 bolt flange but the kit includes a 3 bolt flange. all you have to do is cut off the 2 bolt and weld on the 3 bolt flange that should fit any race header. i'm still using the 2 bolt since i still have a cat, but i have the 3 bolt flange sitting in my room next to my silencer whenever i get a race header.
 
#22 ·
I called KSeriesParts today and he said that the reason Skunk2 went with a 2 bolt flange is that most people use the RR with a downpipe or the Skunk2 race header which has a 2 bolt flange as well so they pair up nicely. He said that they have tried to work with Skunk2 about creating an adapter but Skunk2 is not interested in doing that.

Thanks for complimenting my whip btw, she is slowly getting there and no my wheels are not powdercoated, they are can rattled ;)
 
#26 ·
Well, I sold my 60mm Skunk2 cat-back today and just bought the 70mm.

Should be here on Wednesday so I'm excited for that!

At least I'm 20mm bigger piping than stock ;)

Thanks man, it was a weekend project, nothing special, I'm wanting to get some actual wheels sometime in the future.
 
#27 ·
Update, I just installed my new Skunk2 70mm MegaPower R cat-back, sounds soo much deeper than the 60mm piping and I'm already in love, Skunk2 for life!
 
#31 ·
3" exhaust on non turbo rsx.. add power or not?

I was thinking about doing a 3" exhaust on my rsx. It's non turbo and won't be turbo. Some people tell me that it will be the highest power gain I can get, and that even without turbo "the k20 loves to breath." Other people say I won't gain the most power, and that it is not smart.

I keep hearing it both ways. Now I know there will be a good deal of you that will post and pretend you know what you're talking about (like the people who told me both ways) but hopefully based on your answer I will be able to differentiate who knows what they are talking about for real.

Thanks in advance to whoever answers my question
 
#45 · (Edited)
I was thinking about doing a 3" exhaust on my rsx. It's non turbo and won't be turbo. Some people tell me that it will be the highest power gain I can get, and that even without turbo "the k20 loves to breath." Other people say I won't gain the most power, and that it is not smart.

I keep hearing it both ways. Now I know there will be a good deal of you that will post and pretend you know what you're talking about (like the people who told me both ways) but hopefully based on your answer I will be able to differentiate who knows what they are talking about for real.

Thanks in advance to whoever answers my question
I am not claiming that a 3" exhaust does not make power. You said it best, evidently the proof is obvious. The K20, relatively speaking is a high compression motor; the k20a2 for instance with it's OEM 11.0:1 compression is equivalent to a 9.5:1 motor with approximately 6psi+ of boost which means it can only benefit from a bigger diameter exhaust. However, what I am saying is this; in terms of price vs. performance, if you already own a perfectly functioning 2.5" exhaust there technically is no point in upgrading unless you have deep pockets or you are just seeking every ounce of power you can get going N/A; as the power difference between 2.5" - 3" is not a huge gap if you are using stock internals. To me, $700+ for 5-8whp is not a worthy upgrade and I think that money would be better spent elsewhere unless you are already in the market for an exhaust.

There are also different factors beyond overall power to take into consideration, most of the CRSX community use their RSX as a daily driver, and we all know a 3" exhaust is certainly far from being low profile. For many people such as myself, maintaining a low key/profile is worth more than an extra few ponies as that can become a huge inconvenience, in terms of law enforcement.

What's quiet enough for you, maybe very loud in many areas and vice versa.
Look dude no one is telling any one to upgrade form 2.5 inches to 3 inch. I agree, that would be a waste of money in some cases. The person that I quoted above you is in the market for an exhaust so we are advising him to get a 3 inch, that's it.

edit: And your claim, to be exact, is that going from 2.5 inches to 3 inches with a basic bolt on setup will lose torque, which is false, period. That's is what your first post said, hence the ensuing argument.
 
#34 ·
You WILL NOT lose torque.

Read the thread under yours about custom exhausts and you will see this is a generally accepted fact.

3 inches > 2.x inches over the whole powerband
 
#37 ·
YES. I know from experience, don't listen to people saying less backpressure kills torque, it's not true.

http://www.veryuseful.com/mustang/te...Scavenging.pdf

Read that article and if you want read over this thread as well

http://forums.clubrsx.com/showthread.php?t=838397&highlight=inch+exhaust&page=2

edit: It also depends on what header you're running. I first got my custom 3 inch when I still had the stock header, and I literally gained butt loads of torque. With a race header you WILL STILL GAIN torque, though not as much as with the stock header, I think the stock header is designed specifically to build torque.
 
#41 ·
OP just listen to those of us that know from experience and actually own 3 inch exhausts, all of us will tell you the gains are worth it, and that you will gain torque. Don't be scurrred :thumbsup:

http://forums.clubrsx.com/showthread.php?t=841101

One of the dudes that posted in that thread owns an A3 and he also loves his 3 inch...
 
#44 · (Edited)
I am not claiming that a 3" exhaust does not make power. You said it best, evidently the proof is obvious. The K20, relatively speaking is a high compression motor; the k20a2 for instance with it's OEM 11.0:1 compression is equivalent to a 9.5:1 motor with approximately 6psi+ of boost which means it can only benefit from a bigger diameter exhaust. However, what I am saying is this; in terms of price vs. performance, if you already own a perfectly functioning 2.5" exhaust there technically is no point in upgrading unless you have deep pockets or you are just seeking every ounce of power you can get going N/A; as the power difference between 2.5" - 3" is not a huge gap if you are using stock internals. To me, $700+ for 5-8whp is not a worthy upgrade and I think that money would be better spent elsewhere unless you are already in the market for an exhaust.

There are also different factors beyond overall power to take into consideration, most of the CRSX community use their RSX as a daily driver, and we all know a 3" exhaust is certainly far from being low profile. For many people such as myself, maintaining a low key/profile is worth more than an extra few ponies as that can become a huge inconvenience, in terms of law enforcement.

What's quiet enough for you, maybe very loud in many areas and vice versa.
 
#50 · (Edited)
Haha yeah clearly I'm illiterate cause you can't understand what I'm sayin... The fact that it says Mustang doesn't mean shit, too bad the link's broken it's a great article.

Clearly you can't read cause I already said I'm not gonna waste my time or money proving anything cause that would mean I have to do dyno runs with 3 inch and then go buy a 2.5 inch exhaust (yeah right, why woud I do that...) and do dyno runs with 2.5 inch with same other mods on the same day on the same dyno. Fuck dat.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top