Depends on how much money you want to spend. There's a big difference between a $50 air filter and a $180 set of UD's. However, you'll probably get more performance from the pulley's for now but you still need to get the K&N in there, too. It's not that much, just do both. You'll gain more hp with the pullies than with the filter.
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1994 Red SVT Lightning #2019