I've had my old 91 F250 2wd with a 351w and zf5 for quite a few years now and just recently dropped in a new crate motor due to some pretty bad problems with the lower end. I've gotten quite a performance boost from what she used to be "when she was running on practically 6 cylinders" but I'd love to do something more without investing an arm and a leg into her. I just dont know what to do tho. It's all stock except the exhaust which is hollowed out cats and two 20" cherry's on a dual exhaust with an x before cats and cherry's. I've looked around a bit and was looking into a cam but I don't really know what I could do without upping the injectors and what not. If anyone could lend me some knowledge it would be greatly appreciated!!! Everything is new under the hood with roughly 10k miles on it so anything I could just swap out under $500 to get a noticeable difference would be super.