The whole idea with aftermarket exhausts or no exhaust is to free up the flow, which in some cases can improve power. But that's the balance. Your car may or may not need so much backpressure. In some cases loss of back pressure can cause loss of top end.

Straight exhaust really serves not a lot of purpose unless you know that your car is running MUCH better without it because you've done some kind of crazy mods or something like that; but even then it would be hard to justify straight exhaust unless you knew it was doing the engine way better (most likely it's not).

Speaking to the noise... Well, yes, obviously cars are going to be WAY louder without any exhaust; plus as far as I know, you have to have a cat. and muffler to pass emmissions.

Back to the noise thing... 4 cyl can be noisy w/o mufflers but come on, it's an Accord 4 cyl. It's not going to be like a NASCAR V8. My buddy runs no muffler on his WRX wagon in Solo II and it actually sounds great and not that loud (still under allowable/rebulation dbs).

Best advise... Get a muffler.

HTH.