I have a 72 240z that I bought 8 months ago the car is very fast and responsive it already has an electronic ignition,
anyways I change the coil to a high performance coil and I notice that the car started having a smell kind a like unburned gas, or may be a leak on the exhaust, I think that maybe the exhaust system may need to be upgrade to add heaters and a 2.5 pipe I think the stock exhaust can't keep up w the engine??????

there is no doubt that a bigger exhaust and headers will make more power ....

maybe your carbs are running a bit rich (in reguard to the fuel smell) are you sure u got a coil for electronic ignition and not a 240Z ???

Rusty Datsun x 2
1x Bronx Grey 260Z 2+2 (Soon to be blue)