The external engine braking mechanisms used on diesel engines are there to compensate for the lack of compression braking that gas engines inherently have by design. The basic difference is that gas engines restrict the inlet air flow when you lift the throttle, while diesel engines restrict the fuel flow. That air flow restriction and resulting "compression braking" is what the external "Jake" type braking systems on diesels duplicate. To get the full compression braking effectiveness on a gasser, just drop it out of overdrive and downshift as needed for the conditions.
Dutch
2001 GBM Landau 34' Class A
F53 chassis, Triton V10, TST TPMS
Bigfoot Automatic Leveling System
2011 Toyota RAV4 4WD/Remco pump
ReadyBrute Elite tow bar/Blue Ox baseplate