Installed TS catback, have drone, anything I can do?

[heymanwatchthis]

Hello all. I installed the Top Speed Pro 1 cat back exhaust. All my stock cats are still in place.

I have a loud drone between 2,500 and 3,100 rpm. Car is a '01S.

Anything I can do about it? Any hints to improve the drone? Everything else sounds good but the drone is quite loud and annoying, if I can get rid of it all is good.

I wonder - I used some steel about 1.5" long to lower the mounting bracket as it seemed high to me. I did not want to tilt it down with spacers. Wonder if the slightly less support from bracket contributes to drone?

Thanks!