To Decat or Not to Decat that is the question

[oldskiddy]

Ok chaps I am pondering de catting my exhaust system.
Is it just a case of opening it up, ripping the guts out and re welding?
Give us a clue please, I have a man with a welder standing by, stainless of course.

Thanks

 

[Giles]

Some peepes have done this.

The general theme of conversation around it was that some said they'd done it and there was no problem, and that others reckoned that an empty cave in your exhaust pipes would be bad for all the flow, harmonics, back pressure and all of that guff.

Clearly de-catting your bike will really help the exhaust gasses flow and will give you better performance (and MPG), but whether you should DIY or buy proper de-catted down pipes ... ???

I don't know ..

Glad to have been a help ..

 

[BBB61]

Header pipes do come up on Ebay that have already had the cat removed so that is another option. It would allow you to keep the standard headers to put back on the bike when you eventually sell it.

 

[Fanum]

Rip the fucker out

 

[oldskiddy]

Thanks for clearing that one up

I thought it was just a case of cut, remove, weld. Maybe i'm wrong on that one.

Any other opinions out there?

Thanks

 

[BigAl&Andri]

De-cat

Just last weekend I put Keihan headers on my '08 GS. Seems like there's a little more urgency about the bike now and I like the slightly less agricultural exhaust note. However, my fuel gauge has gone AWOL for some reason. It may be purely coincidental but it's a bit annoying. Anyone else had this experience?

I'd still go for the de-cat though. Next stop Hilltop M/Cs for a remap!

Al

 

[masterman21]

I have just fitted Akro headers to my 2012 tc. Big mid range improvement as has been the case with my last 3 GS's. Does make it pretty throaty ! but is still smooth an manageable .

 

[oldskiddy]

ok thanks all, I shall be keeping an eye out for a pair of de catted exhausts.

Thanks

 

[Fanum]

Ok, I was brief but I'll stick by it.

Ask yourself what it's there fore......

A) to pacify the greeny tree hugging lesbians by keeping the emissions lower.

Does it do anything FOR you?

A) No, unless you value the opinions and esteem of the tree hugging greeny lesbians

What are the downsides of ripping the fucker out?

A) Green tree hugging lesbians will frown at you
A2) Your bike won't run quite as sweetly unless you re-tune it to allow for the change in air flow/fuel mix

What are the upsides of ripping the fucker out?

A) Less weight=higher power to weight ratio (the thing weighs about 5kg!)
A2) Lesbians of the green persuasion won't become your friends anymore
A3) You MAY get better power out of your bike because it will run better when re-calibrated to take advantage of the tree hugging greeny lesbian limitations on its breathing that BMW were forced to adopt.







Just make sure you re-calibrate the fuelling by one of the many and oft-repeated methods contained in these hallow pages, and cancel your membership of the weekly Greeny Lesbian tree hugger's club

 

[oldskiddy]

Nice post.
As for Greeny Lesbians, well I have lived near Brighton before. I think they run the council now. Bless em:cool

Ok im keeping my original down pipes and silencer. I have a REmus coming just looking for some decatted downpipes.

Thanks

 

[BBB61]

Nice post.
As for Greeny Lesbians, well I have lived near Brighton before. I think they run the council now. Bless em:cool

Ok im keeping my original down pipes and silencer. I have a REmus coming just looking for some decatted downpipes.

Thanks

I have a set of the Keihan decat front pipes for sale if you are interested.

 

[Deleted account 190920001]

Just last weekend I put Keihan headers on my '08 GS. Seems like there's a little more urgency about the bike now and I like the slightly less agricultural exhaust note. However, my fuel gauge has gone AWOL for some reason. It may be purely coincidental but it's a bit annoying. Anyone else had this experience?

I'd still go for the de-cat though. Next stop Hilltop M/Cs for a remap!

Al

What on earth do you think getting rid of the CAT could possibly do to screw up the fuel gauge?
The damn things break every 6 months, you should be happy you got this long if it is the first one to go.

 

[Bendy toy]

I have a set of Remus headers that are a straight swap so you can put the bike back to standard if the need ever arises.

 

[BigAl&Andri]

What on earth do you think getting rid of the CAT could possibly do to screw up the fuel gauge?
The damn things break every 6 months, you should be happy you got this long if it is the first one to go.

Don't think I actually said getting rid of the cat had screwed up the fuel gauge - just that it was something of a coincidence. Anyway, I am happy that it's not gone wrong in over 5 years. If yours goes every 6 months I'd value your advice as to how to re-set it or is it a replacement job (which sounds very expensive)?

Al

 

[Nick dj]

De-cat

I did de-cat a stanard set of headers on an 08 very easy and quick, did improve pick-up.

I have a set of Akropovic headers for a 10/12 twin cam, if you interested?

Nick

 

[Bobbin-Man]

I did it ... see this thread
I bought a s'h set of headers and removed the cat, I was very happy with the result so I later sold the original headers. I fitted an accelerator module as well to increase the fuelling a tad.
The pick up is better particularly two-up at cruising speeds, smoother at low speed and improved fuel consumption. Be wary about fitting after market headers and silencer, it can result in a little too lean fuelling and sometimes a tendency stall dropping down to 1st gear - this might be caused by many aftermarket headers not having the balance pipe at the front. I'm running the standard can.

 

[Bendy toy]

Ive had Remus headers (no balance pipe) with standard muffler and an Akraprovic Ti twin muffler system which does have a balance pipe.

Balance pipes are supposed to help at low/medium revs where the flow down one side creates a suction on the other side. However both felt like they gave similar low and midrange performance. The Akra is loud and has more top end, but Ive not tried the Remus with an aftermarket muffler. I was using Moldex -35dB earplugs so the noise wouldn't be encouraging any fast feeling - I cant hear anything with them in.

Hilltop said neither system (with baffles) will make any significant difference.

Personally I think its probably tradition because BMs have always had a balance pipe. Why change a working formula. Until the oil heads they were usually 2 into 2 which would benefit from the balance pipe.

 

[oldskiddy]

I have a set of Remus headers that are a straight swap so you can put the bike back to standard if the need ever arises.

You have Pm.

 

[(RIP) Arkwright]

Better for the environment without the cat, mine does an extra seven miles per gallon, and has done since I did it in 2007!

 

[STUBBS]

just go for it