The loss of power probably has more to do with IAT than coolant temp. The ECM starts pulling ignition timing, &c, at around 90F IAT. IAT is usually a few degrees above ambient when cruising and can be 20F or more higher when sitting at a stop.
My _guess_ is that the changes made to reduce power are causing the change in exhaust sound level. Maybe the exhaust valves are opening sooner/longer to reduce effective compression.
Last edited by SouthArk370Z; 07-29-2015 at 11:53 AM.
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