I have a AXL Headliner SRO .
Its a Cheap Guitar. Now I wanted to upgrade it but i don't know much about upgradation processes.Freatboard is okay while playing but The main problem is with Sustain its almost terreble.So can you guys please suggest me how to and what to upgrade and how much its going to cost me.
Thanks in advance.
New Delhi, India
Save your money and get something better

you can try raising the pickups that might help you out a little.
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First, remove all the hardware.
Disassemble the body/neck.
Find a wood chipper.

Cost of upgrade will be whatever the new guitar costs.

Seriously, folks...
Sustain in the guitar itself is a function of maintaining string energy IN the strings. Things that will help prevent string energy from being easily transferred or damped include dense body and neck woods, glued frets, heavy/dense bridge/tailpiece components and reduced magnetic flux from the pickups. There's not much of that you can "upgrade" sufficiently on that guitar to increase sustain to any reasonably noticeable degree. You might also need to double check that your frets are level and that your guitar is properly set up.

Question: Do you have a full-size, 3/4 or 1/2 size Headliner SRO? How far is your action off the 12th fret to the bottom of the string (on both the high and the low E)? Do you hear buzzing of the strings when you play?
I have AXL HEADLINER SRO, 3/4 Size.There Is no buzzing noise while playing the 12th fret top to down.

Does Replacing the Tremolo Block would help me?
and if there is no option rather than changing the pickups then which pickup should i purchase.
The 3/4 size has something to do with it (the smaller scale, surely). A larger brass trem block will often help (make sure you get one that fits properly, I have no idea how close to a standard strat trem yours will be). I don't think pickups will be a big improvement.