Sorry to hear that.  I have not ever needed more power to go on any incline.  My Cforce 450L has plenty of power to keep going even on mud but I have never try driving in it in deep sand reason why I never needed much speed at all.    You might be able to get the machine to run better for your needs with a clutch kit from either "Main Street Cicles" https://www.mainstreetcycle.com  or "Red Neck Garage" https://rngperformance.net.  Give them a call and explain your problem cause they have a couple of kits that would give you different results.

Awesome thanks....Took my 2020 Cforce 450L for service and the adjusted the brakes and made it almost imposible to shift in and out of park/reverse.  They messed up with that cable on the foot rest for no good reason at all.  Now with this info I am able to re-adjust it to not need that much pressure any more.  Big thanks and amazing a post this old still helped in 2023

lol Im 100% good to get the atv stuck

On my 2020 the ECU is under the seat, on the left side of the machine right next to the battery.  I can take a picture if you need so just let me know. 

Think that is normal operation as mine has always done the same but once I hit the ignition the light goes away.  Been a little over two years and never had a problem with it.

This is for a 2020 machine...hope it helps

Yeap the 400 has the CVT air intake right under the dashboard cluster. That is a pretty good spot for the intake as you get clean air and it is also mounted very high off from the ground to not get water in it.  The exhaust air pipe of the CVT is actually on the back left side behind the tire.  Be careful as you might actually get water in your CVT transmission if you get that pipe underwater which I have done a couple of times in some mud and water crossings.  Funny thing is that I got water in through that pipe, the exhaust one and not through the intake pipe.

Hey Bma2022

So apparently you can put 27" tires but it depends on the rims..

Check this video at 4:12
https://www.youtube.com/watch?v=ju-mKydbefQ&t=289s

Yea I just use the original bolts and the lens stays in place without any glue or other sealant.
Does your brake light works properly?  When I use the hand brake ass soon as I squeeze the brake the quad slows down and the brakes are engaged yet it takes about half of the travel for the light to come.  When I use the pedal I have to press it harder to get the brakes and again it slows down way before my brake light comes on.

Mine lets me go pretty fast on reverse.  Will check and report back.

I took me for ever to move to inches and finally was able to hook the winch.

Yep, once you break them free the first time all the others are much easier to disassemble. 

Had surgery and had not ride this year.  Finally was able to go out today and it was awesome...got stuck in the mud and everything. 
Fitted some cheap remote controls for the front and the rear mounted winch and they are not reliable at all.  Any of you guys have issues with remote control winches?

Cool video man

My hood had a lot of missing tabs when I got it.  Looks like no one know how to take them off properly.  Any way, it really helps if you spray some WD40 or any other lubricant on those rubber grommets to get the plastic pegs to pop out and actually slide back into place again.