Question: Muffler Delete - Back Pressure

Hey!

I just got a 2005 RX-8 a few weeks ago and the first thing I'd like to look into doing is upgrading my exhaust system. I've done research on here and other sites but there's so many opinions. (figures, here I am asking for more opinions... not really)

I'd like to hear from people who have eliminated their muffler.
1) What'd you replaced it with? 90 degree? Y? other??
2) How did eliminating the muffler affect the engine, how it drove, etc.

I haven't seen anything speaking negatively of the muffler delete other than how load it is. I'm okay with that tbh. But when I took it to a muffler shop in town, I was told he doesn't recommend it because the car apparently needs the back pressure the muffler provides.
Is he full of BS and wanting me to drop a few grand in a cat back, or does he have a point?



Lastly, since I know some of you will chime in and say don't take the muffler off, what type of upgrade would you suggest? I'm not looking to spend more than a few hundred dollars right now and the less the better. That's half the reason the muffler delete is attractive.

Thank for your time!