Catted H- pipe HP Gains?

Hi,
My MAC catted H pipe came in Saturday probably putting it on Monday evening. I am thinking a 10 to 15 HP increase. Will dyno in a couple weeks.

What do you think??

Lowered (Eibach 52/94), Cold Air Kit, Under Drive Pullies, Ford 3.73 Gear, Steeda Tri-Ax, Flowmaster Exhaust, Mac Shorty Header, TFS TW Heads, Steeda 19 Cam, Cobra Intake, FMS 65mm T/B, Pro-M 75MM MAF, Steeda 24# injectors, H&S 1.72 Roller Rockers, MSD 6al, Blaster coil, Walbro 255 LPH, Timing chain and Gear

Hi,
Didn't want to be changing it all the time..
The install was put off for about a week today, My grandson is sick and I use my son and his lift for the work.

Steve