Bigger brake discs on my Gary Fisher Wahoo? (203mm baby!)

Hi all,
Before I say anything else, very cool site! can't believe I've not signed up before now!
I hate to kick off with my very first post as nothing more than a grovelling attempt at finding a few scraps of information, but needs must!
I'm relatively new to the world of the modern MTB scene (I used to do a lot of XC trails and mild downhill stuff moons ago!) but recently got back into it, I bought myself a 2007 spec Gary Fisher Wahoo (teeny tiny frame, get low!), I love the bike to bits, it's great for how relatively little it cost. There are a few things I'll change on it over the next few months, but they're really out of personal preference rather than needful.
Which leads me to:
Brakes! it's fitted with Shimano M465 mechanical calllipers and 160mm discs, they're not actually too bad, obviously a lot better after everything bedded in though!
I wouldn't mind a little more stopping power though, but I don't really want to fit hydraulics, so after some searching, I found a few parts which I thought I may be able to mix and match, but I could do with someone confirming, or blowing my ideas out of the water!
I found: some Shimano 'Saint' 203mm discs (centre lock as per the ones already fitted to my bike) a universal alloy calliper spacer (looks strong enough and supposedly caters for 160/180mm to 203mm coversions) and some carbon metallic pads to fit the M465 calliper. It's a fairly common practice to fit bigger discs on cars retaining the stock callipers and spacing them as required (been there), but is there any reason why it might not work on my bike? so far it all looks peachy!
All comments happily taken onboard!
Before I say anything else, very cool site! can't believe I've not signed up before now!
I hate to kick off with my very first post as nothing more than a grovelling attempt at finding a few scraps of information, but needs must!

I'm relatively new to the world of the modern MTB scene (I used to do a lot of XC trails and mild downhill stuff moons ago!) but recently got back into it, I bought myself a 2007 spec Gary Fisher Wahoo (teeny tiny frame, get low!), I love the bike to bits, it's great for how relatively little it cost. There are a few things I'll change on it over the next few months, but they're really out of personal preference rather than needful.
Which leads me to:
Brakes! it's fitted with Shimano M465 mechanical calllipers and 160mm discs, they're not actually too bad, obviously a lot better after everything bedded in though!
I wouldn't mind a little more stopping power though, but I don't really want to fit hydraulics, so after some searching, I found a few parts which I thought I may be able to mix and match, but I could do with someone confirming, or blowing my ideas out of the water!

I found: some Shimano 'Saint' 203mm discs (centre lock as per the ones already fitted to my bike) a universal alloy calliper spacer (looks strong enough and supposedly caters for 160/180mm to 203mm coversions) and some carbon metallic pads to fit the M465 calliper. It's a fairly common practice to fit bigger discs on cars retaining the stock callipers and spacing them as required (been there), but is there any reason why it might not work on my bike? so far it all looks peachy!
All comments happily taken onboard!

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2006 Specialized Enduro Expert
http://www.pinkbike.com/photo/3192886/
2008 Custom Merlin Malt 4
http://www.pinkbike.com/photo/2962222/
2008 GT Avalanche Expert
http://www.pinkbike.com/photo/3453980/
I thought it might work to be honest, but it's nice to have someone else say it will aswell!
Did I mention I'm a cheapskate?!
The 203mm setup should be ok for now, can't beat a bit of extra leverage! (pardon?!)
Orange Patriot 66 FR
Clubroost XC-4 (retired)
Pinkbike
My Biking Videos
Or even Tektro Aurigas, CRC are knocking them out for £40 each, assembled, bled and ready to go!
Help for Heroes
JayPic
Personally, I'm not sure I'd want all that extra weight on the wheels on such a light bike, you might love it though.