i upgraded recently my Cm.031D with the following:

Guarder SP130 spring
SRC Metal Spring Guide with Bearing
Element Alum Piston Head with Bearing
Metal Shims and Bushings
TU Lipoly 1450mah

the rest are stock - plastic piston body, air seal nozzle, cylinder head, gears, hop-up rubber...

scenario -
after a few rounds in skirmish (average of 2-games), i've heard something is wrong with my internals! I suspect some loose gears!!!oh no....so i have it checked with my reliable gunsmith.....

he opened the gearbox....to our surprise, the stock piston body's teeth are gone!!! should i say, "naubos or napudpod" ....huhuhu.....also, the support end of the alum piston head break....tsk, tsk, tsk.....

our assumptions are that, the stock plastic piston body of cyma is to weak to handle SP140 spring, due to its stiffness...

solution -
so we have it repaired and change the damaged stock piston body with JG Brand full metal teeth (orange color) with built-in Piston head. This is the recommendation of my gunsmith, since this JG piston body is well tested and reliable...he uses this with other set-up like SP140 and up...

NOW, we haven't torture tested the gun to its max....just on plinking and chrono testing only...it has a good rof and fps rocks at 484 on 0.2g....

I will let you know, after my game this weekend...and will try to post an update/outcome....

Is my present set-up ok? will this JG brand can last on with my SP130?

What would you say, KOMRADS?

Yeah, stock piston body, sira kaagad yan sa sp120 or pdi190 spring komrad.
Since then, kasama na yan sa spring upgrade ko ang new piston body.

On my CA i have been using it still with Sp120 set up. The other 1 has systema m120. Both are still ok. I guess mahina lng talaga stock ng cyma,dboys and JG.

@komrad bounty hunter-- Mukhang mahina ata sa sp140 pag 480+ lng sya. Dapat nasa 500+ yan.

Btw im moving this to HELP.

I was advised the same thing. madali daw makasira ng stock piston body ang SP120. I'm using the WELL stock piston body... as advised by a friend gunsmith... - kasi mas matibay he said.

kom moky, i mean its SP130 po.....
you mean komrad, it can go beyond 500++fps, with SP130?.....hmmm....considering sealing all possible air leaks?......

Updates!

Komrads, finally, I was able to torture test my C.031D last weekend...No Problemo!....Good ROF, fps at 480+- using TU lipoly 1450mah batt....internal set up with Guarder SP130, JG full metal teeth piston body, SRC spring guide with bearing, Element Alum piston head with bearing, the rest.....stock components.

thanks Komrads to some of your inputs...