S2R Decat power loss

31-10-2009, 09:28 AM

Hi, I'm on the verge of parting with some of my hard earned loot on a marving decat pipe. I've heard that you lose some bottom end with them, can anyone shed some light on this? is it something you can feel, or is it just a statistic?
Thanks in advance.

Capo · 31-10-2009, 09:43 AM

I've heard of leak problems with this pipe

31-10-2009, 11:10 AM

I've got dyno run printouts for with and without the cat. You do lose a few ft/lbs torque at low revs, all you gain from the de cat pipe is more a few ft/lbs torqe in the mid range, more noise and losing the weight of the cat itself. I didn't notice any difference apart from the extra Dbs.
My bike actually made half a horse more power with the cat still in place!

Hope that helps

31-10-2009, 11:37 AM

My Marving was fitted last week to my S2R.... The only slight leak is from the front header pipe, some silicone sealant should sort this... I had to reuse the old 'brillo pad' gaskets, i would recommend using new ones...
I haven't noticed any power changes, increase or decrease, just a much better noise... I have carbon Termis and it now sounds great.....

The Marving fitted perfectly....when I got the mechanic to fit it for me!!

31-10-2009, 11:58 AM

I can't give you a definitive answer as I fitted the decat, open race cans, open airbox and hi-flo filter al at the same time, and then fitted a PC3 and had it set up on the dyno. My mid range was much smoother.

Overall I gained very little on paper but it felt well worth it.
My figures are in this thread, post #4
http://www.ukmonster.co.uk/monster/s...highlight=dyno
I had the PC3 mapped again recently and got 77bhp and 58 ft/lbs torque.

31-10-2009, 12:01 PM

Quote:

Originally Posted by Jim66a

I've got dyno run printouts for with and without the cat. You do lose a few ft/lbs torque at low revs, all you gain from the de cat pipe is more a few ft/lbs torqe in the mid range, more noise and losing the weight of the cat itself. I didn't notice any difference apart from the extra Dbs.
My bike actually made half a horse more power with the cat still in place!

Hope that helps

Is it possible for you to post the readouts? also, were you still using the standard silencers?

I'd love a set of high level carbon termi's, but unfortunately I value my nuts and I'd probly loose 'em if I spent that much!

31-10-2009, 12:32 PM

I have a decat pipe fitted to my S2R (Quat d not Marving) with standard cans and I definitely felt like I lost some torque at lower RPMs. Ray at Rosso Corse said it had something to do with the back pressure the cat generates, i.e. no cat = no back pressure = less torque. A PCIII set up correctly may have helped to some extent but I bought a pair of high level termis instead and I've regained some of the lost power. Power delivery isn't as smooth as stock but it sounds so much better

31-10-2009, 09:39 PM

Hmmm thanks for the feedback, I've got a choice, for the same cash I can get a 2nd hand pair of std silencers and have them cored. But would that be better than a decat ? I guess I'd have to keep the carbunkle then tho...

gary tompkins · 31-10-2009, 09:51 PM

Open or cored pipes + cat won't increase noise a lot

The cat acts a silencer and you won't get the full effect until it's bypassed

01-11-2009, 11:22 AM

Has anyone ever tried to gut the cat?

01-11-2009, 11:28 AM

Gary's comments are spot on.. I bought Termis fro my Multistrada, and left the cat, it didn't sound any better.....
The Termis on my S2R didn't sound very good, but with the cat gone they sound great.....

Never heard of anyone trying to take the innards out of the cat....and you would still have the ugly cat box there....not worth the time and effort when the Marving is 195 pounds....

Zimbo · 01-11-2009, 12:35 PM

If it's performance and smooth running you want and you're on a budget, your first purchase should be a Power Commander imo - get the fuelling right to go with what you've got (even straight out the factory and bog standard the fuelling can be improved quite a bit).
Get the PC remapped each time you make a further mod (decat etc) to make the best of the system.

01-11-2009, 04:38 PM

Yes, I agree, a PC3 is on the christmas list, but a more lusty roar without actually losing anything is the name of the game at the moment.. I tried just taking off the silencers/link pipes and the cat does seem to do a little silencing, but its still a bit too anti-social to run it open!
(And I think VW tail pipes run straight off the carbunkle would make it all look a bit too scrapheap challenge for me!)

Does anyone have an opinion on the amount of lost bottom end power felt with the decat pipe? Noticeable? barely noticeable?, very noticeable? I can't imagine there being much difference between makes, after all its just a bit of pipe bypassing the cat made by different people aint it?

31-10-2009, 09:28 AM	#1
Bigxr Guest Posts: n/a	S2R Decat power loss Hi, I'm on the verge of parting with some of my hard earned loot on a marving decat pipe. I've heard that you lose some bottom end with them, can anyone shed some light on this? is it something you can feel, or is it just a statistic? Thanks in advance.

31-10-2009, 09:51 PM	#9
gary tompkins 1/2 man - 1/2 pogo-stick Join Date: Aug 2002 Location: Dartford, Kent Bike: M900ie Posts: 7,241	Open or cored pipes + cat won't increase noise a lot The cat acts a silencer and you won't get the full effect until it's bypassed __________________ GT Fully paid up member of the S.A.S. (Scottoiler Appreciation Society) 27,000 miles on original chain - and still going strong!

31-10-2009, 09:43 AM	#2
Capo You Are What You Is Join Date: May 2005 Location: A Foward Location Bike: S4r Posts: 1,948	I've heard of leak problems with this pipe

31-10-2009, 11:10 AM	#3
Jim66a Guest Posts: n/a	I've got dyno run printouts for with and without the cat. You do lose a few ft/lbs torque at low revs, all you gain from the de cat pipe is more a few ft/lbs torqe in the mid range, more noise and losing the weight of the cat itself. I didn't notice any difference apart from the extra Dbs. My bike actually made half a horse more power with the cat still in place! Hope that helps

31-10-2009, 11:37 AM	#4
jimbo696 Guest Posts: n/a	My Marving was fitted last week to my S2R.... The only slight leak is from the front header pipe, some silicone sealant should sort this... I had to reuse the old 'brillo pad' gaskets, i would recommend using new ones... I haven't noticed any power changes, increase or decrease, just a much better noise... I have carbon Termis and it now sounds great..... The Marving fitted perfectly....when I got the mechanic to fit it for me!!

31-10-2009, 11:58 AM	#5
Gilps Guest Posts: n/a	I can't give you a definitive answer as I fitted the decat, open race cans, open airbox and hi-flo filter al at the same time, and then fitted a PC3 and had it set up on the dyno. My mid range was much smoother. Overall I gained very little on paper but it felt well worth it. My figures are in this thread, post #4 http://www.ukmonster.co.uk/monster/s...highlight=dyno I had the PC3 mapped again recently and got 77bhp and 58 ft/lbs torque.

31-10-2009, 12:32 PM	#7
Duke Konan Guest Posts: n/a	I have a decat pipe fitted to my S2R (Quat d not Marving) with standard cans and I definitely felt like I lost some torque at lower RPMs. Ray at Rosso Corse said it had something to do with the back pressure the cat generates, i.e. no cat = no back pressure = less torque. A PCIII set up correctly may have helped to some extent but I bought a pair of high level termis instead and I've regained some of the lost power. Power delivery isn't as smooth as stock but it sounds so much better

31-10-2009, 09:39 PM	#8
Bigxr Guest Posts: n/a	Hmmm thanks for the feedback, I've got a choice, for the same cash I can get a 2nd hand pair of std silencers and have them cored. But would that be better than a decat ? I guess I'd have to keep the carbunkle then tho...

01-11-2009, 11:22 AM	#10
Bigxr Guest Posts: n/a	Has anyone ever tried to gut the cat?

01-11-2009, 11:28 AM	#11
jimbo696 Guest Posts: n/a	Gary's comments are spot on.. I bought Termis fro my Multistrada, and left the cat, it didn't sound any better..... The Termis on my S2R didn't sound very good, but with the cat gone they sound great..... Never heard of anyone trying to take the innards out of the cat....and you would still have the ugly cat box there....not worth the time and effort when the Marving is 195 pounds....

01-11-2009, 12:35 PM	#12
Zimbo Too much time on my hands member Join Date: Apr 2003 Location: Stonehouse, Glos Bike: Multiple Monsters Posts: 2,085	If it's performance and smooth running you want and you're on a budget, your first purchase should be a Power Commander imo - get the fuelling right to go with what you've got (even straight out the factory and bog standard the fuelling can be improved quite a bit). Get the PC remapped each time you make a further mod (decat etc) to make the best of the system.

01-11-2009, 04:38 PM	#13
Bigxr Guest Posts: n/a	Yes, I agree, a PC3 is on the christmas list, but a more lusty roar without actually losing anything is the name of the game at the moment.. I tried just taking off the silencers/link pipes and the cat does seem to do a little silencing, but its still a bit too anti-social to run it open! (And I think VW tail pipes run straight off the carbunkle would make it all look a bit too scrapheap challenge for me!) Does anyone have an opinion on the amount of lost bottom end power felt with the decat pipe? Noticeable? barely noticeable?, very noticeable? I can't imagine there being much difference between makes, after all its just a bit of pipe bypassing the cat made by different people aint it?