The way we did it in "the old days" was first to free up the exhaust. I had a 1971 Pontiac LeMans with a code YS 400. It was rated at 300 horse power. I took off the restrictive exhaust manifolds and put on a set of headers. Went the rest of the exhaust (dual of course) with 2.25" and put on free flowing mufflers. I took off the stock Rochester carb (it leaked from the stripped fuel line fitting - a lot of them did) and put on a big Holley double pumper. It was so powerful it was scary. Must have been pushing 500 Horse power. The biggest gains are from freeing up the exhaust on engines like that. What's a Ranger have? a 302 V-8? a V-6? Throw on a cheap set of headers and some free flowing muffs, it's a guaranteed 30% more power. Drive responsibly of course.