All sounds like hard work to me. Personally I've got this stuff:
http://www.commaoil.com/Product%20Pa...leting/awc.htm
You can pick it up in Halfords too.
Literally just spray it on, wait a minute(if your downpipe is rusty then agitate it like the instructions say with the brush thats provided) and then rinse it off. Hardly any elbow grease needed at all.
Just make sure you don't get it on the paintwork or breath it in.