Tail belt & battery question

[r_cpilot]

I'm planing on putting a T-rex tail boom on my MX400 so I can use the 325mm blades and I know I need a longer belt. Will the stock T-rex belt work or do I need to get the Heli-Max long belt.

I am using an Align 430L (3550kv) with an Align 35A ESC and I had planed on using 2100mha 15C lipos. When my batteries arrived they were 1700mha 15C, will these work ok? I an new to helis so it will be a wile before I'm doing even basic aerobatics.

Thanks for the help

[Thorimmortal]

you should be fine with the boom and belt I prefer the align boom and mx belt , as far as lipos what brand are they , the 15 c battery's should be fine as long as the cont. amp rating is higher than what your heli draws, those 1700 bats should work they should have an amp rating of 25.5 cont amps (mah x 15c =25.5) I like the thunder power 2070 extreme cells , or the flight power packs.