Newbi Question

I am planning to get my first PTW this week.  Before that can someone help me out with the following:

1) is modification to the buffer tube needed in order to fit stick shaped lipos?  does the buffer tube need to be cut?  I presume 11.4v with 15c would be good for regular max version with 110m spring?

2) i am considering to get the URB stock to go with the M4, which version would fit ptw? mil spec or pts gbb version?  similar to Q1, any modification needed for using lipo?

3) are the factory assembled ptw worth the extra 2-3k?  i am confident in assembling one myself, shouldn't be hard at all, but i heard those finished ptw are better in terms of quality.  any in sight?

thanks in advance!!!

1. buffer tube size lipos are avaliable in market, u dont need to change the original buffer tube if u juz wanna fit the lipo inside the buffer tube, but u need to replace the original curly power cable into a straight one. BUT if u wanna use another non-comm'l spec butt-stock, that's another story.....BTW 7.4v lipo will be good enough for M110, we use 11.1v for M130 or above usually!
2. non pts version will recommand, but about the mod of UBR for PTW is too complicated, i'm not qualiflied to give u the answer about that...
3. the answer is NO, if u dont have any tools for the charllenge kit, then find a PRO to assembly for u, juz cost u few hundreds labour fee.....

thank you so much sailun412!! it's nice to have something experienced to provide newbi like me insights.  

guess i don't need new battery as I have 2 7.4v 20c lipo sitting around. i will probably get a set of 09 max challenge kit now and assembly it myself.  i actually think putting a one together is a joy and it shouldn't be that hard, at least according to the guide i see from systema US.  

As for the UBR, i can always come back on this to figure it out later........

u r always welcome here, as here is the only little corner for the local PTW "老同(s)" like us, & welcome to the REAL world dude!