I've heard I can increase bhp to my 1.8 16v zetec xr2i by replacing the ecu, throtle body and cams.

If this is the case how easy are the parts to fit (how much am I likely to get charged as i;m no mechanic).

Also do all three mods need to be done to see any benefit or will each on its own show an improvement in power?

Thanks for any help/advise