HP4 exhaust system

Hi Guys and gals,

This may have been asked a hundred times before but i cant find the particular information i need, right i want to get rid of the cat off my HP4 but im a little confused firstly i want a titanium link pipe but not sure where to get it from, then im in two minds whether to keep the akrapovic end can or replace it for a Austin racing or similar can (purely for looks and sound) but dont know if this even possible while keeping the rest of the Ti system, and then whats best after ive had it done, to get it power commandered (PCV ?)or the equivalent. Its not going to be tracked much but more street use. I have found snippets of information but would like to know from people in the uk and how they have achieved this, it doesnt seem that many people play with the HP4.

Many thanks for your time and patience reading this

Hi Chris. I went down the decat link pipe route on the standard (lol) full ti system for two reasons: 1) weight saving, which is a lot, and 2) engine can breathe easier so theoretically runs a bit better. My experience is that both are true. I didn't bother with a remap because BMW told me it was a small enough change that the ecu self adjusts. The bike runs with a deeper tone and feels that it revs a little easier, the weight saving was noticeable too. Having said that, IMO the bike will improve with a good remap so that's top of the list of wants at the moment .

The other thing to consider is noise. I got black flagged at snetterton early this year on drive by, baffle fitted. Takes a little bit off the fun having to shortshift around a place.

All engines run different, I would think for road riding this would be ok, because I track a lot and and usually max it out I have de-cat and pcv with which I had it dyno'd and mapped. Glad I did because it ran too lean at full throttle. Kept the exhaust valve for noise testing which has always been 98db, been flagged once in12mnths for drive by.

soofsayer said:

Hi Chris. I went down the decat link pipe route on the standard (lol) full ti system for two reasons: 1) weight saving, which is a lot, and 2) engine can breathe easier so theoretically runs a bit better. My experience is that both are true. I didn't bother with a remap because BMW told me it was a small enough change that the ecu self adjusts. The bike runs with a deeper tone and feels that it revs a little easier, the weight saving was noticeable too. Having said that, IMO the bike will improve with a good remap so that's top of the list of wants at the moment .

The other thing to consider is noise. I got black flagged at snetterton early this year on drive by, baffle fitted. Takes a little bit off the fun having to shortshift around a place.

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Hi excellent thank you for your help,sorry just a couple more questions, where did you get your link pipe from, did you do the heel guard mod ? Also do you know if any of the other cans will fit straight on to the link pipe i,e Austin racing or the arrow sytems ?
Sorry for all the questions but new to the 1000rr and only modded a GSXR before now and the HP4 is a bit special and want to get it right first time.


Cheers again guys.

Many thanks, where did you get your work done, im portrsmouth based.

Hi Chris. No problem with the questions.

The link pipe is akrapovic I believe.

I got mine from the bmw dealer and they fitted it for me. I would have saved a few quid buying it myself and fitting (which is simple to do but will require taking the belly pan off), my thinking was that if they fitted it I would be covered under warranty for any issues arising from it (no issues to date).

Yes I did the carbon heel guard mod.

This guy over the pond sells them, thats where I got mine from. The thread below is fairly comprehensive about the decat etc. Explorer still owes me hard cash for the heel guard clips I sent him - plus interest.

http://s1000rrforum.co.uk/showthread.php?4078-HP4-Decat-Link-Pipe/page3&highlight=carbon+heel+guard

If any other cans fit the ti system with the cat on, then they will fit with the decat pipe as the diameter and length is the same.

Thank you very much for the info, you have all been very helpful !!

RRChris said:

Thank you very much for the info, you have all been very helpful !!

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Austin have about 4 end cans that remove the cat and have a link pipe. I have done it for lugage. however I think they are too load for track days.

jack sprat said:

Austin have about 4 end cans that remove the cat and have a link pipe. I have done it for lugage. however I think they are too load for track days.

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Ok brilliant thank you