I wouldn't say it was an improvement, just it made the power band a little lower and smoother. With both 1.3s in I had to really rag it to accelerate to keep it in power, with just the 1.3 inlent and stock exhaust cam(as I have a 1.0 engine) theres just no need to rev above 6krpm, and will happily drive at 30mph in 5th.
So it's a bit of a compremise, sacfrifice a bit of top-end for fuel economy and comfort. Think i'm averaging around 40mpg, which isn't bad to say it's drinking like a 1.3 due to the 1.3 inlet cam.
But I think you could get a similar effect by retarding the exhaust cam, so I might put the 1.3 ex cam back in but 1 notch out, so hopefully have more power, but still get a smoother power band, but I don't know if that will work out too well to do it yet!
