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Old 08-21-2010, 02:35 AM
bleudyno bleudyno is offline
Join Date: Oct 2009
Location: Fullerton, CA
Posts: 23
bleudyno is on a distinguished road
Originally Posted by RTC View Post
Moded exhausts on turbo engines usually have a negative impact on torque and power and ECU mapping adaptations are very often needed just to avoid a torque/power loss. Sad but true. I don't trust tuner claims and dyno readings are worthless if not done under the very same conditions. A change in air pressure due to the weather can already change the results substantially. I actually don't trust dyno readings at all...unless they are done on the engine (which of course is much more expensive and time consuming). On a turbo charged engine, I wouldn't expect much gain from the exhaust only, on the contrary.

The ONLY way to get a better sound on the X5 M, according to a BMW M GmbH engineer, is to remove the special manifold used for the engine and exchange it with a "regular" one. This improves sound A LOT, gives the car that typical V8 growl but at the same time you loose aprox. 35 HP engine power. Not really worth it.

My advice is: stay away from any ECU/exhaust mods and save your money. It is almost impossible to improve 0-60 mph performance (do 0.1-0.2 seconds really count?) and you get a one second advantage from 0-125 mph if you add 60 horses. When did you guys drive 125 mph lately in the US? Not really worth it. The drivetrain of the X5 M is good for up to 700 Nm of torque. Reliability would go down the drain with excessive tuning, not to mention the warranty. Have you asked your local BMW dealer how much a new engine costs ? Just do it...for your entertainment.

I drive my X5 M for almost five months now on the german Autobahn and so far, I haven't met a car to be faster. Not that they don't exist but the X5 M is only 0.5 seconds slower from 0-125 mph compared to the BMW M3 Coupe, so it is almost impossible to meet a match on the street. Unless you're a dedicated street racer...or 20 years old without any real purpose in life.

Just curious, what makes you such an "expert" on this subject?
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