The problem w/ the 75 is it's difficult to tune since as it opens, it drastically leans out the A/F since the rate of air coming in is much larger than stock. As for Explorers, not sure what year, but I'll assume it's the ones w/ the 2V engine. Headers, attempt this only w/ the k-member off the car or the engine out of the car. Otherwise, you'll end up pissed and giving up like me. But the low-end doesn't suffer to badly but the power comes in strong once you hit 2-3,000 rpm and you'll get better mileage too, city and highway. Shortys don't add much (10hp tops) and for the trouble, might as well spend the cash for long tubes.