 If you liked
Install
|
 ...then you might like
Zankoku na Kami ga Shihai suru
|
They both deal with violent MxM rape and the mental consequences for the victims. Install is a (hard to find) one-shot by Chi-Ran while Zankoku na Kami ga Shihai Suru (A cruel god reigns) is over 84 chapters long (so far) and written by Hagio, Moto.
The artwork in Zankoku is definitely older when compared to that of Install, but as the series progresses it starts to improve. It never really becomes "modern", but things look less rough and over time the story distracts you from the dated drawing style.