Siamese or Twin exhaust ?

[Viking]

What is the difference in engine performance between Siamese or Twin exhaust on the S/R / RGS engine.

I have fitted my SR with RGS tuned engine with a Twin super rocket type exhaust system.
Considering a Siamese system to boost performance.

Eddie Dow “are on about” Siamese is best for full throttle action at peak RPM, and twin system ( with megaphones) is optimal for medium RPM.
http://bsa-a10.hailwood.com/tt11.html

What is your experience ?

Any dyna test ?

[bill harrison]

I have a Siamese system on my RGS (replica).  I reckon it makes absolutely no difference!  Also makes one side of the bike look a bit bare IMHO.  Sounds nice though.

[PaulC]

I have Siamese on my SR. Looks good, sounds great and only half the amount of chrome to polish!

Never tried it with twins, so I have no idea about performance.

Paul

[worntorn]

I replaced my old dual pipes with Siamese pipes and a straight thru Goldie exhaust, what an improvement in power!
Not a fair comparo I realize as the old left hand pipe had this huge crimp in the underside of the pipe. The bike is new to me and I hadn't spotted this restriction until removal of the oldpipes to fit the new.
I can leave the 23 tooth engine sprocket in place. Was about set to reinstall the 21 in order to retrieve a bit of power.

Glen

[bobandbec]

My preference is for twin but purely from an appearance point of view. In fact just removed a siamese arrangement on one of mine to replace with a twin. Probably don't go fast enough to tell if there was any difference in top range performance!

Peter

[Topdad]

I'm the same, fitted Siamese system with straight through goldie ,lovely noise even the none biking neighbours come out to experience it or at least that's what I think they were shouting  .I too run a 23 tooth engine sprocket and she pulls like a train and the sound at a few thou revs , doesn't take much to keep me happy as you can tell.

[Rocket Racer]

I can only comment I have Siamese on both my A10's for both the track and the road.
 For the road I consider improving ground clearance on the LH side a useful plus,
 for the race sidecar it doesn't matter but improves accessibility on the primary side

[taylor1960]

Im in the same boat 2 into 1 or 2 into 2  i like the look of 2 pipes with short megaphones Loud Pipes Save Lives