Forget the Modify 110 spring and go with either a 90 or a 100 (I've made AK's shoot 370fps and nicely with the 100 and a bearing spring guide). Avoid getting close to 400fps, it serves no purpose other than to prevent you form playing, or from having shitty performance. It's a limit, not a goal. And a 100 will be nicer to your battery life as well.
As far as your age and wanting to upgrade, I don't give a shit about it, you listen to the advice given to you about upgrades, all fine by me. The way you act on the field is attached to that, and I think vets running 400fps AEGs is dumb too, 360-380fps is the best performance area anyways. Case in point, all last year I ran my MP5 at 400fps for the first time ever, and found it's range and accuracy suffered. MP5SD with 300mm tightbore etc. Some guns run fine, but others don't, and still, an extra 10-30fps doesn't make a shit of difference for performance. You'll get a huge difference if you go from 0.25g to 0.28g outdoors. If you shoot only 0.20g.................. a million fps boost in your AEG won't imporve things at all.
Upgrade the player and the ammo first, then work on the gun.