Not really i've watched a 03 ex and on 03 blaster stock everything and the 2 kids were 14 and the other was 15 i believe and they both weighed the same and the weight was exactly 157 lbs (we weighed them at the camper). the 14 yr old (less experience) boy was on the 300 ex and the 15 yr old was on the blaster they both were on hard packed dirt running running maxxis whole shot tires but everything was stock and they raced at least 6 times if not more and the ex won every race i know the second time the ex started about 5 yards back and it still won

 

I also forgot to mention the 4th run they switched and once again the ex won so it wasn't the driver

 

That might be but if the ex was piped and jetted and the blaster was piped and jetted. The blaster would come out on top.