question on compression testing yamaha 250hp four stroke

[SanityCheck-27]

I've done compression test before on other engines but was told I could damage the computer modules by not grounding the sparks plug leads first before running the compression test. Is this correct and should I just run a wire lead from each spark plug lead to the engine block?. The engine is a 250 hp Yamaha 4 stroke 2007 not sure what the compression should be on this engine. Thank you for the help Robert

 

[99yam40]

most just pull the kill switch to stop spark while testing