The Sword and Laser discussion

First off, sorry if this is in the wrong place, I'm on mobile at work and it's hard to navigate. I'm trying to find the name of a sci-fi book I read several times as a teenager. I can't remember anything about the author or name of the novel, I can't even tell when it was published. I remember the cover being the hero with kind of a spiky mullet standing in an alley, very pulp. But I do remember a bit of stuff about the book itself, and was hoping someone could help me out.

It was post apocalyptic, with the world having been conquered by alien parasites that attached themselves to the brain. The hero at one point gets attached to one, but somehow beats it because he's to some degree mentally ill(?). I remember them having to use fire a lot to fight them. The only other thing that stands out was that he had some type of machine pistol that he had modified to be fully automatic with a penny - I only mention this because I remember the description vividly, having read it at the time and wondering how the hell that was even possible.

I'd appreciate any help. I've been thinking about it a lot lately and I'd like to reread it and see if it's as good as I remember.

Parts of this sound like Heinlein's The Puppet Masters, parts do not. Good luck.

Is this the cover? The Parasite War by Tim Sullivan

Dang, that's it. Thank you so much. I had done some scattered googling to try and find it, but wasn't coming up with much. I highly appreciate it.

No problem. Glad I could help. :-)