I've shortened my air intakes, so here's some pics...

[mrTickle]

Yeah, mine is also backfiring far less than it used to ( I'm not keen on the backfire though, so I'm happy about that ).

I double checked my throttle balance after doing this mod, but they were still perfectly balanced. I also reset the TPS sensor just in case.

 

[BiG DoM]

If you want to go faster maybe you should sell the GS and buy a sportsbike.

My understanding is that tubes give better and smoother low down torque - trimming them will give more further up. I must say I have tried mine without the extensions (you do not need to cut them as they are moulded seperately and are a push/clip fit - needs a bit of force but can seperate the two parts...this way the mod is reveresable) and my sphinctum dyno seems to indicate a bit more torque but maybe also subjective and also because slightly noisier.

Anyone fitted the bigger RS tubes ??

 

[The Mechanic]

Take a look.

Oh well I suppose something must be right but not according to the BMW manual Rob Lentini pages 87 on (? I think). Here he fits GS intake pipes to his RS and reports better performance, and he backs this up with a dyno print out as well.

 

[Roge]

I've seen somewhere that fitting the longer tubes to an RS or RT gives more mid range at the expense of a little top end. I've got shortened tubes and can't say that I've noticed a lessening in mid range but the bike seems to pull better all through the range and certainly above 5000rpm

 

[Panzer Patrol]

And if you want larger diameter tubes the same length as the shortened GS ones, stick in the tubes from the RS. Works for me

 

[simonm]

Re: Longer pipes

The flutes (curved edges) are there to prevent the air being drawn in from literally bouncing off the now flat edge. Add a trumpet to a straight cut inlet and power increase, not dramatically but by at least 2-3%.

The installation instructions for the BBPower chip recommend shortening the inlet on the RH side only AND not smoothing off the cut
They claim this helps tilts the power curve slightly - you gain a little top end HP and lose a little low down torque.
When I installed the chip I ran for a while without the tube mod and then cut it as specified. I also disconnected the Lamda. I can't say my arsedyno noticed any great changes - maybe a slight emphasis but its very very subjective.
I was more concerned with smoothing out the overall curve and ensuring I wasn't running too lean.
Overall I'm very happy with the y-piece+revolution+chip setup

Simon