Ahh soldering irons. Right.
I've got one of those pencil torches somewhere and while they can be used and do get hot enough after a while, there's a hole on the side where you get a jet of hot air that comes out. So one minute, there you are happily soldering away, and the next you've melted a nearby wire or the box.
25-30w is about right for mods. Any hotter and unless your soldering skills are good you'll melt something.
I found 25w a little low for soldering the silver connectors I have as it takes solder a bit longer to flow so got one of these
http://www.ebay.co.uk/itm/ANTEX-ER-...rden_PowerTools_SM&hash=item2c6c236b47&_uhb=1
Or get tesco points
http://www.tesco.com/direct/antex-er-30-30w-corded-wired-soldering-iron-brand/124-3167.prd
Or these are quite dinky, akin to using a large pen
http://www.ebay.co.uk/itm/ANTEX-XS2...rden_PowerTools_SM&hash=item1c2ff26ec9&_uhb=1