Internally the only differences between the HO and truck motors are the cam and pistons, the HO cam has more lift and duration and the HO pistons are forged vs cast but compression ratio is the same for both. Externally the truck intake is WAY bigger than the HO so it's not a bottleneck at all, but the truck exhaust is a big one. More HP from a truck motor is dumb easy.. swap in a better cam and change the whole exhaust system.. BAM... you got 260-275hp. But it's still a mouse motor pushing a vehicle that is on average 1000-1500lbs heavier than a mustang so don't expect Mustang performance.. that takes 50 to 100 more cubes or a supercharger and lots more axle gearing.