1600Dp Spacers under cylinders??

My Beetle is quite loud, not overly loud, just louder than i would like, especially when i put the foot down. I bought a stainless twin gt exhaust which has no leaks. I'm just wandering if its detonating or something wierd to do with mixture, timing and compression. When i rebult engine i noticed there wasn't any shims/spacers under cylinders like there were on my kombi's 1641.
Would you say i need to strip and rebuild and check deck height and all that to be sure????? Or should i just perform compression test to see whats happening. What sort of figures would you be expecting for a stock 1600DP compression wise.

you should have worked out the compression Ratio when assembling the engine checking deck height and combustion chamber size

doing a compression test will not tell you this only that you have the same compression in each cylinder