That should work. The SDRs have become very popular......many off the self solutions. Never thought to look there.

They probably have many more SDR apps now too. It changes so fast.

Edit: https://www.amazon.com/s?k=FM+band+trap&dc&qid=1551088393&ref=aw_s_fkmr0

 

i got updates:
This morning i noticed a few things about my filter and rtl notch FM filter:

At 108 MHz the attenuation of both filter are high
at 122 MHz the attenuation of both filter are the same
Above 122 MHz my filter doen't reduce the attenuation meanwhile rtl filter does

I thought about theese things and i improve a Little bit my filter.Now:

I get -1.5dB at bandpass (145-150Mhz), i get a BW of 53 MHz and i get -40 dB on 108MHz which is enough to mostly kill the signal.
I attach the new transfer function(S21) of the filter.