Torque peak optimizer (TPOs) performance (dyno charts)

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I have tried Michael Morse’ (650Central) torque peak optimizers (TPO) to improve the flow on 1.75” headers and they made a great difference.

After my 700cc upgrade, I had significant reversion issues with 1.75” headers with 26” commando mufflers and stock air boxes . Switching to stock headers made the exhaust system flow much better and leaned out the bike by getting rid of reversion (https://www.xs650.com/threads/700cc-kit-with-a-shell-1-cam-in-a-78xs650e.65405/). Here is the dyno of the 700cc setup without TPOs (blue) vs stock (gray curves). That was pretty disappointing.

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The dip in AFR between 4 and 7pm is reversion.

Adding TPOs moved the gas much better and leaned the bike out as well as gained performance.
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Note that in all cases with 1.75” pipes I have Heiden tuning/Mikes XS torque inserts at the exhaust port side.



In the end with the Torque inserts at ex. port and the TPOs, the performance is almost as good as with the stock headers. I think with some tweaking I would get the modded 1.75” headers to match the stock.

Another note, all of the tests here are with the stock air box, K&N stock replacement filters.

Here are all the curves and configurations

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Now I am in the process of opening up the intake and exhaust. Stay tuned. I have some suspiciion that the reversion issue was made worse with the 26" Commando mufflers as I found them quite restrictive (https://www.xs650.com/threads/found-a-torque-monster-within-my-bike-dyno-charts.66076/#post-838493)



And some photos of the Torque peak optimizer inserts:

Here is one header with the optimizer reducing the ID from 1.63”to 1.25”.

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This is the installation option where the entire insert fits into the pipe. For this, the inlet of the TPO had to be ground down for the header ID:

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