The Unofficial BMW M5 Messageboard (m5board.com) - View Single Post - Just intalled Sec 1&2 MST GT Exhaust -Loss of low end torque?

Meisterschaft · 27th August 2008, 21:27

previous independent dyno runs, we and our customers have tested,
we have gained close to 8 peak torque gains as well as HP gains
with section 1 and 2.

Loosing out the low end torque was somewhat expected,
since you just have lost close to 25% of back pressure (with passing cats, resonators and high performance muffler system), but the other turn, you have gained on high peak RPM Range instead - that is the advantage of less back pressure especially on NA vehicles such as M3, M5 and M6.

Dyno testings are done numerous times, and even with a 4 wheel mustang dyno, it is fairy difficult to measure numbers when the RPM is low. Below 3000 RPM it can be considered very fragile data and can not be dependent on, therfore, we would not be able to extact tell you, you have gained torque or lost torque based on 3000 or less rpm range testings (lower RPM ranges), however all exhaust systems out there, whichever brand it is, if the exhaust needs to serve high RPM range gains, this is somewhat expected.

To regain, the low end torque, we would recommend you to replace the stock cats back on - replace back with original section I. You will have the low end torque back however most likely not feel as fast on high rev RPM range and slower throttle response.

Also, it takes a little bit of time for ECU to adjust your new settings.
The vehicle needs to learn the new flow rate, which will be re-calculated by your F.L ECM. Drive it around at least next few hundred miles, and see if the ECM adjust properly. If you still think the setting is not what you are looking for (power within lower RPM range) then put the original section I catted pipe back on the vehicle.

P.S
have you installed any aftermarket headers?
The reason we are asking: performance headers will break loose another close to 10-15% back pressure.
Indepent dyno runs, we have several results of loosing power in wide band of RPM Range.
Folks with section 1+2+ rear section 3, we recommend not to use any aftermarket headers,
unless you want to remap your ECU and rev it 8.5K for prime peak (with higer octane race fuel) with
weight reduction of vehicle is recommended to better rate the torque.

If you have any questions,
please call us. We should provide you more specific guidelines for you.
thank you.

GTHAUS: 630.787.1600

27th August 2008, 21:27	#7 (permalink)
Meisterschaft Company Representative for Gthaus Join Date: Apr 2007 Location: GTHAUS Posts: 181 Thanks: 66 Thanked 9 Times in 8 Posts	previous independent dyno runs, we and our customers have tested, we have gained close to 8 peak torque gains as well as HP gains with section 1 and 2. Loosing out the low end torque was somewhat expected, since you just have lost close to 25% of back pressure (with passing cats, resonators and high performance muffler system), but the other turn, you have gained on high peak RPM Range instead - that is the advantage of less back pressure especially on NA vehicles such as M3, M5 and M6. Dyno testings are done numerous times, and even with a 4 wheel mustang dyno, it is fairy difficult to measure numbers when the RPM is low. Below 3000 RPM it can be considered very fragile data and can not be dependent on, therfore, we would not be able to extact tell you, you have gained torque or lost torque based on 3000 or less rpm range testings (lower RPM ranges), however all exhaust systems out there, whichever brand it is, if the exhaust needs to serve high RPM range gains, this is somewhat expected. To regain, the low end torque, we would recommend you to replace the stock cats back on - replace back with original section I. You will have the low end torque back however most likely not feel as fast on high rev RPM range and slower throttle response. Also, it takes a little bit of time for ECU to adjust your new settings. The vehicle needs to learn the new flow rate, which will be re-calculated by your F.L ECM. Drive it around at least next few hundred miles, and see if the ECM adjust properly. If you still think the setting is not what you are looking for (power within lower RPM range) then put the original section I catted pipe back on the vehicle. P.S have you installed any aftermarket headers? The reason we are asking: performance headers will break loose another close to 10-15% back pressure. Indepent dyno runs, we have several results of loosing power in wide band of RPM Range. Folks with section 1+2+ rear section 3, we recommend not to use any aftermarket headers, unless you want to remap your ECU and rev it 8.5K for prime peak (with higer octane race fuel) with weight reduction of vehicle is recommended to better rate the torque. If you have any questions, please call us. We should provide you more specific guidelines for you. thank you. GTHAUS: 630.787.1600 Last edited by Meisterschaft; 27th August 2008 at 21:36.