Please need suggestion on these muffler?

Hello !
I bought the muffler, is the best muffler that I ever had before. It looks awesome! During installation I remove the catalytic too. When testing the muffler, it makes a deep deep sound during low rpm until almost 5k it becomes some weeeeeeee… but not so loud. I felt some increase in the car power, I’m not sure if it’s a psychological gain but I felt it! For example, when accelerating fast and when shifting from 1st to 2nd, my tires make a screech sound like if it increased the car’s power, but I will see if it lowered my time in the 1/8 of mile until Saturday night and I’ll post results. Last Saturday 11.18s..

Thanks!