I'm looking into getting 2 MTX TR75's but i don't know whether i should get the 2ohm or the 4ohm subs.
is there a power handling difference? The subs are 500 rms and the amp is 1000 rms at 2ohms.

 

You'll want to get 2ohm subs.

 

But say if i wanted to run 1500watts at 1 ohm for a short period of time like at a comp?
which is better then?

 

You can wire up two 4ohm DVC subs to have a nominal 1ohm load. What amp is it? Are you even sure the amp is 1ohm stable?

http://www.rockfordfosgate.com/rftech/woofer_wizard.asp

 

if the amp isnt 1ohm stable you wont have much luck trying to run it at a comp with out it going into protect. you can run a 1ohm stable amp at 2ohms but you can run a 2ohm stable amp at 1 ohm

 

the amp is a MTX TE1501D
500watts rms at 4ohms
1000watts rms at 2ohms
1500watts rms at 1ohm

 

get 2 dual 4ohm woofers and you will be able to run 1500w daily.

 

but will that overheat the subs since their rms is only 500watts each?

 

just keep ur gain set a little lower and you'll be fine

 

whatever happend to the argument that power does not blow speakers? and why do people tell others to set their gains low to avoid this? my pioneer deck has 2v outputs.....with the lack of a dmm i set my gains to the highest setting, which is +9 (of the available 0, +6, or +9) on my alpine mrd-m501.

the best protection for your drivers is your ear, if they're bottoming out, or are distorting, then you know you have problems. The sundown audio nightshade for example is a high end competition sub rated at like 1000rms(or around there) but can take 6000+watts on burps and be fine......power does NOT kill subs