What would everyone recomend for exhuast system for a 98 S90

Well your not turboed. Thusly that means backpressure is your friend.

1. You will not gain much Hp from an upgraded exhaust system on an N/A vehicle.

2. What you will gain overall is sound.

3. I suggest you have a local muffler shop create you either a mandrel bent 2.25"-2.5" catback system with a baffled muffler such as a Flowmaster. Or have your local muffler shop make you a crush bent 2.25"-2.5" catback system with a baffled muffler such as a Flowmaster.

my car wont sound like a honda civic with a fartcan ( huge exhuast) will it? and how much hp will i actually gain for my money?.. 2 hp? 10 hp?

Generally adding exhaust will not give you any noticeable horsepower, prob around 3-5 rwhp max, but will be normally half the weight of the stock system and is mainly for sound and visual purposes. lol. Idk if it would sound like a fart can but I sure hope not.

If your looking to get an exhaust for hp gains, there are many other ways to gain more hp formuch less $$.

You will gain an estimated 2-10 Hp yes.

It shouldn't sound like a RICER car. Just don't go too big in the exhaust pipe and get a baffled muffler.

Magna flows sounds Awesome on the Volvo 5 cylinders.
Not real loud just a little rumble.
Not that much louder than stock.

Tech, thanks for the info on the 5 cylinders, but mine is actually a inline 6.

I know but it would sound about the same as the 5 cylinder.