upgrade m24 javelin
 

I want to know if this upgrade kit is good http://www.evike.com/product_info.ph...ducts_id=35641
I dont know if is good piston and spring guide.

That will fit in the gun but why do you want to upgrade the spring and piston? The difference is negligible and trust me the money is better spent on upgrading the hop up and inner barrel. On top of that the site says that will get you shooting 500 fps, which is too hot for most fields unless you have your certification.
The inner barrel you posted will work fine but if you are using a 6.01 tightbore you had better be using the best of the best bb's. that's really up to you though.

I know I will buy a pdi hop up and inner for my javelin, but the piston are plastic and I want to change that. For the fps, I play with my friend in wood we are 30 but we dont have max fps but if it higher 500 - 550 we will not accept. I want to know if this kit is good I know he fit in my gun but my upgrade will cost 200$ but if I bought this kit I will save 35$ but the other piston I find is laylax and angel custom.