what whitestarlet said. not many people seem to realise the difference between the two engines... the fhe has a totally different wiring set up compaired to the 5efe. whereas the 5efe has almost identical wiring to the 4efe... hence why whitestarlet said it was easy. the fhe uses a separate coil*, different distributor(4efte)*, higher lift cams, different exhaust manifold & downpipe, different inlet manifold with idle control valve (4efte)*, larger injectors, and a different throttlebody (4efte)* *all use different wiring to the 4e/5efe. you could possibly get it running using the 4efe loom if you use the 4efe: distributor, throttlebody, inlet manifold, injectors and ecu. but you would need to do something about the fueling like maybe a adjustable fuel pressure regulator with the fhe injectors, and then you would still only have a rev limit of 6k, and then you'd probably have less power than the 5efe.