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      10-28-2009, 09:58 PM   #45
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Drives: E90 M3
Join Date: Nov 2005
Location: Los Angles (818)

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Originally Posted by Rom3n View Post
Unless you are running a full catless exhaust system there is 0 need for a custom tune. The engine management system in this car eliminates the need for custom tuning it actually wont let you custom tune it like the old days. With multiple input signals this engine management system calculates corrections on its own, you simply tell it what AFR targets you want and it will execute the corrections to achieve it. Where you can gain a little power on this stock motor is by setting ideal timing / AFR targets, adjusting the cylinder noise levels and adjusting VANOS controls. These targets are the same for ALL stock cars. How a motor was broken in or how it was put together makes no difference.

When you run a full catless exhaust you can set custom targets to take advantage of the less restrictive exhaust and remap the VANOS control to correct for overlapping due to loss of back pressure. This is done by collecting data on the exhaust system with several dyno runs, comparing them to the original baseline and making corrections based on how that particular design is affecting performance and where there is room for improvement. This process when done correctly takes time.
Well I agree to an extent makes no sense to try to get a custom tune on a stock car to me thats a waste but if you're going all out then things change and imo requires a custom tune. All of my previous experience has proven this since I had a catless system installed as well as pulley,airfilter etc. It made a huge difference for me and a few other people I know but thats just the way it goes.