pull your plugs and have a look at the color,white is lean,brownish grey to light brown is good and sooty or black ir rich. From what you describe you are probably just a little lean. Maybe an adjustment to the mixture screws would do it or maybe that and 1 shim on the needle. You haven't done much of a change to the way it breathes stock so probably not way off. As for popping you may also want to check the exhaust gaskets where the exhaust meets the head to make sure they are tight. and look fo any sign of dry rubber on the intake such as intake mounting rubbers and the vacume caps.

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