Anytime you open up yor exhaust by enlarging the size you will lose HP in the lows. Think about it, our engines feed off of a certain amount of back pressure in the lows. This must remain or you WILL lose(.)
What feels and sounds good doesn't always mean HP/TQ gains across the entire band without any losses.
This would be a different story though if you were running NO2, Street Flight Turbo, or Vortec supercharger.
I haven't heard anything but horror stories from any of these! Maybe NO2 in small amounts 50/75 HP shot would be good!