im replacing my headgasket and cant decide weather i should get the buddy club .5mm or 2.0mm head gasket. its an ls/vtec setup. with a thicker head gasket does it raise or lower the compression? and which one would be better. thanks

 

Thicker = lower compression, thinner = higher.

The best choice depends a few things...
1. what pistons your are using?
2. has the head been milled, and if so, how much?
4. are you using aftermarket cams, and if so you need to think about piston to valve clearance.
3. what do you want your final compression ratio to be?

Pretty much you need to figure out what your compression ratio would be if you used a stock thickness headgasket, and then choose the HG thickness from there if you want to move the C/R either up or down.

 

 

http://www.zealautowerks.com/bseries.html

use this calculator to get a ballpark of where your compression will be, there are also calculators for d,k,h/f series.