I have had my Chevy for a while.I don't race the car and just like to drive it on special occasions. The engine is a 396 bored to a 402CI.It has forged pistons,crank,rods.The heads are stock ported oval ports with 2.19 and 1.88 valves.Not sure what the compression is but it has never overheated.OK,when i used my Top Gun Nitrous system for the first time about 8 years ago i shifted into 3rd gear and hit the button.I was blown away from that blast of a drive through 4th through my Muncie M-20,I was amazed at the power!!!I had a Holley strip dominator on it then.Now I have an Edelbrock Torker 2 on for better throttle response.I have a slightly bigger cam now(574-588 now> 595-595 lift) and the bigger valves.The strange thing about it was the car was running terrible with the 650 Holley double pumper carb on it.When i put new plugs in it they would foul out seconds after starting the engine up.The cure was getting my 650 rebuilt by TCI or some company with a T in Texas I believe.It flows 785 rather then the 650.It has a 4 corner idling system.My plugs after years finally were not fouling out but when I used the Nitrous it was nothing compared to when I used the untouched 650 Holley!!!.I use a 150 shot of Nitrous.I use 94 octane gas.I am running about 16 degrees at idle and my question is should i back off the timing by 6 degree's???s