no no other mods are needed,  The install is fairly easy and anybody with a little bit of mechanical ability could do it in less than 2 hrs.. Hardest part is determining were you want ot place the bottle etc.  we usually run a 12hp shot, kryptonite seen what it does at dumont I dont remember lengths but it was no secret after that.
at the 300 ft races we ran  a 30hp shot.
we like it because it is simple works and its there when you need it and stock when you dont.