It'* be loud, but it'd sound like ****.
I've run my engine with just headers, and when the engine was running kinda shitty, it sounded REAL nice. But now that I have her tuned up and everything working properly, she just sounds like a ricer with just headers. It sucks.. badly. Trust me, you won't want that. It isn't that loud, anyways.. like I mean it won't hurt your ears or anything, but as long as you keep the RPMs low in town, you could probably get away with it. But I wouldn't do it. Like MOS Said, it'd decrease performance, because of a loss of backpressure.
Not worth it. Leave it to the guys with 400ci engines, moving 4x more air than we are.
'89 SSE - GX3 -190k, 155k on body - Back for another ride.