pete they wont flo too much more mate, thing is the steel wheel just allows them not to turn to dust with all the heat, the power gain is in being able to push em harder...but dont forget that they are designed to flow from factory at a paticular range anything over 13-14 psi to much energy is converted to heat (hence stockers ungluing and vibrating apart @ 15-16 psi *of course we've all pused em alot further but without gains*) @ 14-15 PSI with a set of your nice pipes you'll make most efficiant power levels there are ways of using these boost levels more effectivly though i can't get into that here.... ps i'll be ordering a set of those pipes soon