Thanks, Dan! I was surprised at how "easily" I picked up the IFN myself - it was obvious in my luminance subs without any stretching. Now, this image was also a bit of an experiment - I've been frustrated with most of my galaxy images, as the background have always been a challenge, turning up noisy or mottled or what have you. I decided to bump my subexposure times up to 15 minutes starting with this target instead of my usual ten.
That said, my M88's background is comparatively even *despite* ten-minute subs. I guess it's because I shot a ton of them!