Pros
- 450 hp and big boost in torque, especially at low-end
ITS AMAZING!
- nicer (throatier) sound
ESPECIALLY THE WHISTLING!!!!!
- Doesn't dramatically alter exterior appearance of the vehicle
XCEPT FOR THE BADGE! 
- Even with this add-on, I'd be way ahead financially vs. buying a new X5 and modifying it to comparable performance level
Cons
- Cost (15K+ Ouch!)
MORE THAN THAT, ADD INSTALLATION
- Wear and tear - is the suspension/transmission, etc. of the stock 4.6is up to handling that additional power?
I HAD TO REPLACE MY TRANNY ONCE ALREADY. BUT ANOTHER STOCK 4.6 FRIEND OF MINE ALSO REPLACED HIS, SO I DONT THINK THAT WAS LINKED TO THE BLOWER ADD ON.
- Doesn't dramatically alter exterior appearance of the vehicle
- Resale - rumor is that people don't like to buy used X5's with Dinan kits because they assume the car has been driven aggressively by prior owner[/QUOTE]
NOT TRUE, I BABY THIS CAR LIKE NO OTHER. I BEAT UP ON THE BEATER 330 H A HA HA HA HA
AS FOR THE ESS KIT YES ITS CHEAPER BUT IF YOUR CAR IS STILL UNDER WARRANTY I WOULD GO WITH THE DINAN KIT. MY FRIEND HAD ESS BLOWER ON HIS 540 AND 40K MILES LATER, HE SOLD THE CAR, HAD TOO MANY ISSUES...IM ABOUT 30K MILES INTO MY DINAN S3 AND NO SUCH ISSUES....ON ANOTHER NOTE, IF YOU ASK ME IF I WOULD DO IT AGAIN, I WOULD SAY NO. ITS BEEN A GREAT EXPERIENCE TO ADD ON THE SUPERCHARGER TO THE CAR ( I WENT FROM S2 TO S3). BUT I THNK ITS JUST BEST THINKING TO BUY A CAR THAT CAN BE THE BEST IT CAN BE OUT OF THE BOX AND THE DEALER'S LOT. ADD COSMETICS ADD AUDIO VIDEO BUT LEAVE THE ENGINE ALONE....JUST MY 2 CENTS