Firmware Update Question NSS+Gsm Magic+NSU(Network Branded 3 to Generic)

Hello Guys,

I'm thinking about updating my phone's firmware. I think I have a network branded phone because there is a 3 appears when I restart the phone.
(The main reason to update to a generic firmware is 3Network doesn't have an Gsm mode only option so the battery goes down quickly also the newer version firm is better right?

By the way I live in US and on T-Mobile contract.

Here is what I got when I typed *#0000#

V 3.01617.0.6
03-05-2006
RM-92
Nokia N80 (54.02)I guess The phone made is China. it says on the original box and then it branded 3.
Also;
Under the battery the product code is 0535682 (Model:N80-1)

My question is: Is it possible to update my phone to generic firmware using NSS+gsm magic+NSU.

If so which product code should I use to update? (I have the smooth stainless one)

Thank you guys.