I have a leaky 91 SW20 G-Limited manual - water loves my drivers footwell! I've been told there's a few rubber bungs that keep the undertray in place and they may have came loose or lost on my car. Yet another leaking hardtop 
I can rule out t-top as I don't have those.
I have however removed my wiper cowl and wipers and cleaned out two handfuls of tree crud from that with the help of my neighbour. I have also removed my drivers side mudflap and partially lifted up the wheel well plastic and scraped some more out of there.
However due to my noobiness I was unable to do a proper job of removing tyre and wheel well plastic and scraping everything out. My neighbour also pointed out that since my steering wheel boot was missing, the water was coming through there.
I disagreed because the carpet beneath it is bone dry, but it could be a possibility. My seals also don't leak whilst I am driving in the rain, but I am going to purchase some 'Gummi Pflege Stift' which should fix my seals. Other possibility is that it is the rear drains, which I assume are fine. There are many guides on here that make mention of removing the under tray but the skill level of the authors means that they only dedicate a sentence or two to doing it.
Could anyone please upload pictures/diagrams or steps for someone who is mechanically nooby so that undertray removal is easy? I have basic tools as well, hydraulic/floor jack axle stands and ratchet wrench/sockets.
The guides I have seen have dead links to pictures.
Cheers guys.