ICS M4A1 Upgrading

[gooseman14]

I am going to buy ICS M4A1 fixed stock (ICS- 21) and I am going to install a Systema m120 spring and springguide with bearings. So I was wondering whether I should also replace the original gears, cylinder, cylinderhead and pistonhead for Systema`s.
Will Star LowCaps, TM LowCaps and G&P MidCaps fit to ICS?

[Donster]

the star low-caps should work fine. no need to replace the gears. drop it down to a Systema M100 spring and put in a cylinder enhancement kit. this will improve durability and airseal, which will probably put you close to the 400fps mark. If you use the 120 spring, you will be over the FPS limit especially if you replace the internals.

http://www.airsoftcanada.com/SpringChart.html

[gooseman14]

I already have those Systema parts in spare, I only want to know whether those are better than ICS parts or should I keep the stock ones?
I am from Estonia and there the speed can be little bit over 400fps to shoot in auto, so I rather but in the m120 spring.

[Death March]

I'v had my ICS with Sysytema gears and I used there MA-56 upper gear box (ICS) that comes with the M120 spring and have had no issues. But the stock ICS gears didn't like the M-120 spring.That being said though,my ICS is 4 years old.I hear the newer ones are better. With this set up put me at 398 fps with .20's.

[Alex Le Chef]

aniway to resume this

im in the same sort of situation m16a3 all that there is in the aeg promotheus thight bore my goal is to reach 370,380 ish as long as it dosent reach more than 400

what spring you guys think is the best ?

also is there other upgrade to put in ?

[Styrak]

Prometheus M110SP or Systema M100.
The Prometheus will shoot a little hotter than the M100.