Hi, i have a 2005 x5 4.8is and it has just about all the options when i bought it (unsure what the exhaust is, but its still stock)

I would like to make this beast even louder and maybe make it have a even deeper growling sound. Don't get me wrong it sounds amazing how ever i would love it to be even louder, what are my options. The one thing i request is to pass the emissions test.

So what can i do, i've heard of many brand of exhausts and i've heard of x-pipes and all that stuff, however i want to buy something that makes it louder while still passing the emissions test. Any suggestions i would rather spend under 1000 if thats possible however i can extend my budget if needed, it would be nice though if there was a cheap option

Any advice to making this car even louder?
Thanks, i appreciate it

 

I've heard Dinan Exhaust and I love it!
Here is the video:
http://www.youtube.com/watch?v=l4eCrJS2hNg

 

I have a 4.6is and did a lot of research on exhaust and here is the deal: Many of the aftermarket kits sound good, but they are expensive, don't really gain much (if any) horsepower and most of the exhaust tips on them don't look as good as the factory tips IMHO. The best option that I have heard (and the cheapest by a large margin!) is to leave the stock mufflers and cut out the resonator and replace with an X-pipe. It retains the cats so you will pass emissions and just amplifies the exhaust note you already have. Any muffler shop should be able to do it for less than $200.