Cheap horsepower/ performance upgrades

Similiar question I know, but what are the cheapest and most basic modifications that can be made to a 1990 240sx stock engine. Any help greatly appreciated. Thanks.

You gotta go w/intake, headers and exhaust...

Unfortunately for headers you only have Pacesetter's as a choice w/the SOHC engine...but they are cheap so that's on your side...but they come painted black and that starts to peel off in like no time flat...so that's against you...but it's your engine bay...no one looks.

Intake you gotta go w/Injen no doubt.

For exhaust...you should go w/either N1 Duals or GReddy MX/SP...stay away from HKS (personally dont like them) and anything generic...you want a TRUE CATBACK SYSTEM for maximum performance gains. 2.5 inch piping is your best bet...dont go 3.0 inches...too much for NA and you will lose torque...

Thanks alot man. Appreciate the help and your time. Now I have a place to start.