one of my friends told me if i put in new cams i would have to change my compression ratio. is this true? im planning on picking up some mx22 for use in a jdm b18c5

 

No, it is not true. A large cam like a Skunk Pro 3 won't be ideal for a 10:1 1.8 liter GSR motor, but you do not need a 14:1 2.1 liter race gas only monster to run cams larger than ITR's.

 

the m22x(x) are a fairly long duration cam, and you'll loose some dynamic compression ratio unless you bump up through milling/decking/pistons/valves.

 

would i have to do all that to bump the compression up or would valves just be fine?

 

No you don't have to do all of that, the c5 has a fairly high static CR as is. Search some info on flat faced valves and look into decking the block or milling the head. Have any engine shops nearby you can drop in to?

 

anyone knows if the valves that come with the mx22's will raise my compression high enough?

 

m22x's will be fine in a jdm c5.

 

anyone have the mx22 in there type r motor?