i tried to do some research on this but didn't find exactly what i was looking for. i am looking to get a manners stock, probably t4a or t5a. is the chassis worth it? i know it makes things simply, but it is like 300-350 over the regular price. just curious opinions on this. also, when looking to order a stock from them, they give you the bottom metal option. is this just the inlet option, not the bottom metal itself included right? and finally, what do you prefer, the t4 or t5 and why? thanks guys!