I already have a bruin 2x4 but thinking about getting a new 400 or 450 just dont know much about IRS I will only be trail riding no pulling .

 

Well the 450 has 20 extra cc's to play around with, the stroke is longer too so more toque. If you ride both, you could tell quite bit of a difference. I'm lucky to have buddies with them so I could tell power difference. I believe the 450 has more goodies like 4WD hi and low. IRS, means Independent rear suspension, you may know that alerady. Both are good for casual riding and well there almost the same thing, Just a bit more power for the 450.

 

Personally I'd get the 450. Difflock is the way to go. I have and 02 Kodiak and man it burns me when I get stuck one of my tires don't turn.
errrrrrrrrrrr.

 

For the difference in price you get a lot more...

421cc vs. 401cc
4wd and 4wd diff lock vs. just 4wd
Hi/Lo Forward gear vs. Hi forward gear
Digital LCD Display with speedo/odo/hour/dual trip/fuel/gear vs. Speedo/odo/fuel guage

and for what like $400 more....definitely worth it.

If you have any doubts about the IRS, just try it out and you will love it. A lot smoother than a SRA and better side to side control.

Matt