improving antenna
 

without actually making the antenna longer, or switching to a fin, is there any better options to improve the reception. its not bad but just looking to make it stronger. all stock wires look fine and antenna adapter for the pioneer HU are tight

You can search for a car antenna amplifier. Or you can get something like this.
Universal Window-mount Antenna AM/FM replacement antenna at Crutchfield.com

might try and go with the amplifier, gotta find one with someone decent reviews lol. amazon isnt helping for highly rated