Twin Slash ovals or Twin Slash Rounds. Which is louder?

I currently have S/E Street performance slipons 80721-09 which some dealers say are not optimum for performance with stage 1. True?

I am going Stage 1 on my FLHR (2011 Road King 103) K&N filter in S/E kit and S/E tuner.

I've checked the net, threads here, hung around HOG meetings and asked dealers but still don't know so....

Any informed answer or comment on these two questions would be much appreciated.

Now come on boys and girls...someone must know!!!!!!

Just hoping for an answer is all.