Have a little question about shims.....

[Nismo4Banger240]

How much do the shims and the wear to them effect engine life/performance? I have my engine apart replacing the timing chain (ka24de 103k miles) and I was considering replacing them to factory specs but $178 dollars from the Nissan dealership doesnt sound very attractive for sumthing maybe not even that neccassary.

Any help is appreciated, so far I have replaced pretty much all the gaskets, belts ect. and want my motor to run fresh:)

Heres some pics of the motor apart if ur interested(sorry there fuzzy but i have a crappy webcam)



Ill be putting everything in and back together tommorow hopefully unless I find out replacing the shims will be worth it.