Use the K & N kit. The last time someone tried the sigma kit they had issues because this kit wants you to use different size jets on the two inside carbs than what is used on the two outside carbs.
K&N Pod filters on my 1996 ZL600 Issues
- Thread starter Paul B
- Start date
R. J.
Supporting Member
Good to know. 
. I've never used SIGMA jet kits. I just heard good things about them. I've used K&N kits in my dirt bikes and quads.
Ed
Senior Member
If you use weaker or shorter springs for the slides, you can avoid the main problem people have tuning CVs without the air box. Drilling the slides only makes the them lift faster and less stable but a softer spring will make them lift earlier to counter the effect of decreased pressure differential at the slide. I'd just go up 3 sizes on the main jets, cut about 20% off the springs and adjust the stock needles as needed.