i'd get a blaster

 

i think you should get him the 250ex if you just have those quads to choose from.But if not i would get a 300ex.The blaster would be good too.Its just that ive heard 2-strokes can blow very easily.I havent had any experiance wit them though.Deffinately not the Trailblazer though cause theyre really wide,heavy and SLOW.I dnt know much about the z250 but i know its the best lookin one.I have a 300ex and i love it.Its plenty fast enough for a beggener.

 

the z250 is 0.1 mph faster than the 250ex, it was in atv rider magazine

 

z250 goes 1 mile more than the 250ex

 

Even with a pipe i doubt you could beat your bro if he got a blaster. My brother has a blaster and he kills his friend on his 250 ex. If your brother is scared to pin your quad's throttle then i doubt he will blow a 2 stroke motor. 2 strokes are not as unreliable as most peoplke say. If you take care of them they will last a long time. Good luck with whatever you choose.