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Old 01-07-2020, 10:07 AM   #3
FoundNemo
 
Drives: 2019 ZL1
Join Date: Oct 2019
Location: GA
Posts: 573
Quote:
Originally Posted by gotswap View Post
for the below, just take the fuse out and no CEL at all

Exhaust - Unplug the NPP valves in the rear, cover the connectors (male and female) with electrical tape and zip tie them up. There will be no CEL (soft code only for NPP valve not functioning, but no light). Results are a nice tone with little to no drone at all at all times and more pops and gurgles throughout the rev range. Very good sounding. Also noticed a very nice throttle response gain at part throttle in all modes, no change at WOT for power/etc though. If you look at the inside of the NPP mufflers (pics online) for 17+ you can see that when the valves are closed, there is an extremely convoluted and poorly flowing pathway for the exhaust which likely is what causes the throttle response drop, as compared to an open valve. You can always plug them back in from time to time to avoid "sticking" for the valves. Do not unplug the fuse 51 or you are likely to have erratic issues and CEL codes fyi (unlike previous gen ZL1's where this worked fine I think).
Removing the fuse can cause issues and CEL's in many instances for 17+ ZL1's, my buddy's car did after a period of time and he had some erratic throttle issues as well (A10 car). Google around. Unplugging the actuators does not (as referenced by the many aftermarket non-NPP compatible exhausts that require unplugging them).
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