Change to 12g OD's ??

So I'm thinking on changing my 14 g ODs to 12g to get more low-end. Is anybody running 12s?  
It's just when I hit the thick mud, I can barely turn them to get through.

i love 12s in a 450...do you have a  aftermarket cdi

Evan, I tried 14, 12, & 10's with different springs and found for my 450 the 12gr and Blue spring gave me the best low-end and high-end.

I have a 660 with stock cdi. I do have Copperhead CDI sitting in a box on the shelf but never needed it since I don't hit the rev limiter too often.  
I grounded the reverse light to the block, will that remove the rev limiter?
Think I should try the 12g?

what size tires

26" Bighorns.
Let me know what you think James. I need to order some other parts too so I'll do it all in one order.
What's the best way to order, phone or email or pm?

So I talked to James about my set up and what I wanted. He suggested i stay with the 14g OD's, put a purple spring in the secondary and use my aftermarket cdi. 
Got it all in today and took it for a drive and I must say, that was some good advise! I now have that low end from 0-10 km. It takes a while longer to get to my top end but I have way more torque on the low end which is where I wanted it. I made a run with stock cdi and then with my copperhead cdi. Never hit the limiter with either one but then again I only had the length of a soccer field to test it out.  Wondering if I should stick with the stock cdi or aftermarket. Is revving this ol 660 detrimental to its lifespan?