what kind of exhaust should i put on my 98 jimmy
i was thinking of going with flomasters 40's but i though that would be
to much any suggestions?

 

are you looking for a complete cat back, bolt on kit, or just mufflers?

 

cheap : cherry bomb muffler
moderate : flowmaster 40 series muffler
medium : Dynaflow cat Back kit
good : highflow cat, dynaflow cat back kit, 40 series flowmaster muffler
fun : custom true duals as close to straight as possible, no cats, with warlock mufflers so you can un-cap them as you see fit to be even louder...
best : any bigger engine/true hot rod with exhaust....

 

x2 on what Curtis said. He pretty much covered everything you could be looking for.

I have a Cherry Bomb turbo exhaust on my truck. It was only $40 and it gives a nice deep rumble at lower RPM. It's not overly loud or obnoxious, but you can definitely hear me coming.
I think the best overall is probably the flowmaster. I just didn't have the cash to fork out for one at the time. It makes the 4.3 sound the best IMO.
There is TONS of info on both setups on the forum. I'm sure there are a few vids kicking around too. Just do a search.

 

My FlowMaster 40 with 2.5" pipeing deffinitally made my truck gain all around power, It also gave it a really loud deep rumble and im really emphasizeing loud. You can hear it clapping off of buildings when I start it. Honestly I had no muffler at one point and the flowmaster was just a tad quiter.