And yes it will matter on the pipe length but probably not with your symptoms I leave the header at the stock length and start by putting the pipe about 3/8" 10mm or so away and then flying it. then i will try pulling the pipe farther away from the header. till it gets to peaky where it jumps on the pipe. then i start bring it back in.

The motor is a excellent engine. Except for the stock rear bearing. Which as i said in a previous post i use the OS140CFI bearing. Also a 3M mintor dual plug cylinder head will fit on the engine. I have used them before with excellent success also using a OSF plug with a K&B1L plug also. Not sure if you can get K&B plugs but the 1L plug is a excellent plug for this engine also.