I am going to be getting a custom dual exhaust job done on my 2001 Bonneville. Ijust wanted to know if I can expect anything as far as perfomance wise. I talked to my guy yesterday and he said he would put 2 flowmaster mufflers to take place of my current one muffler. Can someone let me know what kind of advantages or disadvantages can I expect with this job ?

Run the duel outlet 80 series flowmaster to make yours a duel exhaust....running 2 would decrease performance.

If you go true dual (from the manifolds) you will lose backpressure which means you lose torque.

So I should just have them put one Flowmaster muffler and run a dual exhaust pipe off of that ?

Reduce your pipe size from the cats to 1.75 inch to the mufflers. Then go with 2 inch out the back. It will help reduce the backpressure loss to an acceptable level. You should be fine with this setup.

That'* just what I will do.

Would I get any HP from doing a job like this on my car ?

What? dual outlets from one pipe, one muffler or a 2 muffler conversion?

I had the option on the Bonneville to cut another spacer for another Denali tip on the driver side, and not really have any lost power. But the Aurora is dual muffler setup. Since you are SE the additional tip won't affect overall power gains or loses.

Very good, so it is really just for appearance ? How could I get more power with this job or would I have to go another route ?

If you go dual outlet then ya, its for looks, just like the SSE. For cost effective power adders, well, open things up with a high flow cat converter and performance muffler. Once you get into porting manifolds etc, the prices jump. Stay with the stock pipe though. Don't monkey around with pipe diameters etc