I have been reading about the drz base gasket mod for a z400. What is it? How much is it? Is it worth it?

 

the DRZe dirtbike has practially the same base gasket as the z400, so if you put a DRZe (yes, there is an e) base gasket on the z400 instead of the stock z400 one, it will raise your compression from 11.2 to 12.1. The DRZe base gasket is thinner so it dros the head down a slight bit which boosts the compression.