Any problems running no muffler at all?
 

Would there be any problems with taking the muffler off and running it for a few days to see how it sounds? (i.e seeing if I like a muffler delete without spending the money)

If you're literally taking off the axleback and drive, then yes, you will have an issue. Your rear bumper will melt.
[ame="https://www.youtube.com/watch?v=B7IgBEyxjKc"]Muffler Delete Produces Shocking Results - YouTube[/ame]

If you're taking off the axleback and installing track pipe (like Nameless track pipe) like this photo
http://www.skream.net/stuff/frs/exhaust_after.jpg

Then no, you won't have an issue... other than louder exhaust noise.

I never ran the car without the axleback, but with my muffler delete, its loud, but not overly obnoxious because you still have the resonator and all the cats. I made a video awhile back on my muffler delete, maybe it'll give you a better idea on if thats what you wanna do.
[ame="https://www.youtube.com/watch?v=JbDtjh83nj0"]https://www.youtube.com/watch?v=JbDtjh83nj0[/ame]

Not only is what ichi said about the exhust melting everything in the rear, your also creating a pocket of carbon dioxide pooling under the cars muffler area if you say go on the highway. All it took was 2 minutes for that car on the racetrack to melt it's bumper by the way:


Also here's a sound clip of the berk dual tip muffler delete on my car at 1:33 I got a bit frisky because a fellow FR-S owner was trying to catch up :

[ame="https://www.youtube.com/watch?v=mwskPf8W4TI"]exhaust clips - YouTube[/ame]

I was about to post the same thing as above. I urge you not to do so as to not be a menace to your neighbors

This is what I thought, thanks man.

Just get some UEL and remove everything behind it for the best exhaust noise

Muffler delete can make the sound really loud and annoying. If you just want a nice rumble, try here- http://www.ft86club.com/forums/showthread.php?t=53653