2.5 exhaust

Well I put the 2.5 inch exhaust on last weekend, I bought it from summit it fit well, I guess my question is it sounds a little tinny is this the effect of the size of the pipes or due to the fact that theres no carbon in the pipes to smooth out the nosie? or is it the mufflers? just would like to hear from other members that have installed summits exhaust.

Thanks