well performance feels alot better on the 4efe, before u used to get power at 3000rpm which lasted through till 5000rpm, anything after that and its just making noise and not alot else, whereas this manifold on the 4efe gives bags more torque at 2500rpm, the power comes in shortly after that, and it then pulls right up to the rev limiter at 6200rpm. it may not improve out and out bhp, but it makes the engine so much more useable, its soo much better for overtaking too. economy seems about the same (but mine was terrible on fuel before anyway). Rich.