Don Terrill’s Speed-Talk

Hi all, I am currently restoring a GPz 550 and I would like to fit a stainless exhaust however I will need to get one made up as i cannot find any for a reasonable price.
What I would like to I know is what can Be done to get the most power out of an exhaust in relation to shape, size and style. The original exhaust is 36mm dia across at the head, then down to 32mm for the rest of the exhaust. It’s 1.5mm thick. It’s a 4 into 1 standard and I’d like to keep like that really. I have fitted a stage 2 jet kit to it and am also going to get a stainless intake manifold made up.
They are CV carbs, I’ve heard that they don’t run very well without the air box and all fitted however I’d like to run the bike on this manifold. Can anyone help me on the shape/style for intake manifold?
Thank you in advance anyone!

Its basicly four 125's
I'd take a look into the dirtbike singles and go from there on both intake and exhaust comparisons.

Someone will suggest Pipemax I bet, and thats the way to go if you want specifics.

Be careful with the jetting, it might need more if you are succsessful.

You may find the ones available extremely reasonable after making your own... Or having someone custom build.