Hi SteveA, no I didnt really try any other exhaust, only the initial high 2 x pipes into the peashooters I borrowed off my road bike, as out of three sets of mufflers I have , those ones gave me more mid range, the other two "original" peashooters robbed my midrange.
Yes you are probably right, Jim Comstock posted several videos of him running up and testing a high HP motor using P11 high pipes, so if I had of opted for the 2 separate pipes, maybe I would not notice the difference.
The reason I went this direction was I had a genuine set lent to me to copy , so did that , and very happy with the improvement in midrange and where the max power tops out.
As I am running a standard crank in Maney cases, I dont have to ring its neck to make power, and also as I am not the quickest rider by any stretch, I can still have usable power low down.
It runs a 5 speed TT gearbox.
Just so you know there is no trickery in the engine, due to class regluations I run standard 32mm Premiers on standard length manifolds with standard sized Vv's in a RH10 head. Standard crank in Maney cases, JS Motorsport JS2 cam, his rods and pistons at 0.040" + I am limited to period carbs, although can change the length of the manifolds and this will be the next area I will work on
It is work in progress, the exhaust is the biggest change since I built it , and I only change one thing at a time and check for results, hence slow progress.
I am building another motor(slowly) , it will have NZ made billet cases, FA head, JS internals including one of JS.s new profile JS2 cams , cast iron 880cc barrels, standard weight hi spec crank. Some of these components I already have, head potential at this stage is 84HP and do some flow testing as we speak.
This motor will need a good exhaust to extract the best out of it.