4 into 1 - rejetting required?

I want to install a 4 into 1 on the KZ 650 (minuki carbs)
do I need to rejet the carbs or should it run fine as a bolt on?

What 4 into 1 would you recomend?

I think a good aftermarket pipe will run a little stronger than stock even without rejetting, and will give a little more power if you rejet.

I think Kerker and Vance-Hines are pretty good.

MAC pipes are junk.

A good 4/1 pipe will lean out your system. As anyone will tell you, running lean can cause engine damage. Better to run a little rich than lean. Every bike is different, my 650 with Kerker 4/1 (I run FULL baffle with tight packing), stock airbox with K&N filter runs 105 mains and 17.5 pilots but other people with similer setup may run 110's. Do a plug chop after installing pipe and see how they look. And yes I agree with bountyhunter, Kerker, V&H best choice. Mac is ok but make it your last choice.

Here is a Kerker on ebay if your interested...