General aviation pilot reports confusion after being instructed by MIA Tower during landing on Runway 8L at night to exit left on Taxiway Z. Reporter and his aircraft end up in the grass between Runway 8L and Taxiway K.

Narrative

While I was trying to keep the aircraft straight and aligned with the runway; I was also simultaneously trying to find Taxiway Zulu as I was rolling to a slower speed down Runway 08L. It was dark at an airport that I am unfamiliar with; having only been there in daylight on previous occasions; about a year before the day this happened. It was a challenge to find Taxiway Zulu. Down the runway I could see multiple sets of blue taxiway lights. In hindsight; having studied the airport diagram; it is very difficult to see and identify a safe position to turn from 08L to exit left on Taxiway Zulu (particularly when instructed by Tower and to taxi with him on his frequency). No yellow runway to taxiway center-line marking; and no green taxiway center-line lights from the runway. The turn off is more than 90 degrees; perhaps 140 or 150 degrees; a virtual blind spot from the approach end of Runway 08L during night time. The taxiway location signs for Taxiway Zulu were neither clearly identifiable nor visible when touching down on the approach end of Runway 08L. I think the reason for this is because if a person looks at and studies the airport diagram it is clear that the only true 90 degree taxiway exits are K1 and K10; which are at either end of the full length of Runway 08L or Runway 26R. Taxiways; K6; K7 and K9 are clearly visible from Runway 08L and are clearly the designated high-speed turn offs. However; Taxiways; K2; K3 and Zulu; appear to be clearly visible from Runway 26R and are clearly the designated high-speed turn offs for that runway. Being unfamiliar with the airport; having given best cooperation to ATC in providing the best forward speed on approach; resulted in more than usual floating/flare. Trying to find Taxiway Zulu given these circumstances; was unable to see Taxiway Zulu signs (the only method to confirm which taxiway) and given the other circumstances in this report contributed to the event of the aircraft having veered off the runway and into the grass by eight to nine feet. I think as a safe practice MIA Tower should avoid allocating the high-speed turn-offs that require more than 90 degree of turn to general aviation aircraft; unless prior to landing it is agreed that the pilot in command is familiar and that he is able to best comply. The worst time to expect a general aviation pilot to read back and navigate his/her location on the runway is during the act of landing. This is clearly why at the majority of general aviation airports aircraft exit the runway at a time and location they feel safe; and then establish contact with ground control. I think this suggestion will contribute to runway safety at this airport and will help to reduce these types of events in future across the nation at airports with similar taxiway layouts.