I would definetly get the 440 kit you won't be dissapointed. On the compression side I'm not sure, I would assume you will have a little more power from the 12:1 but then that will be harder on your cam, valves, valve springs and all your top end componets. They will be quicker but you might be better off trying to sell your 400 and buy a 450R. I have raced a 440 ex and he had me off the line but I smoked him after that.
You can get a stage 2 hot cam for about $150 the only down fall is it uses stock rocker and valve springs you can get the HD chromoly valve springs From Duncan Racing for about $150 but the titanium are way better.........theyre around $250 and as far as the rockers go Due to piss poor quality OEM hardfacing it is highly recommended that the stock rockers are welded and rehardfaced to match cams and im pretty sure Duncan also does this for about $75 per rocker........youll just have to check their website!! Oh yea youll probably need shortened guides for it too!!!......Can you tell i have maybe built one or 2 ex's!!! LOL LOL LOL
I had a 400 that had a new 428 kit in it and also a 04 450R, the 450r was so much better, I would never consider a 400 again. You can pick up 450Rs cheap now too. I sold my 04 with 10 trips on it, only in the sand for $3000.
I have an 02 an i was going too go with the 440 kit an i had buddies that said they couldent keep head gaskets at all . so i went small an did the 416 hi com port polish stage 2 cam an pipe an change sum gearing runs on turbo blue .
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