looking to put a single 10in sub and amp in my trunk of my 02 gt it comes with the mach 460 sound system and everything with that system still works. just wondering what the wiring would be like with the mach system in the trunk.
Like above, you'll need a feed coming out of your stock head unit to a AudioControl box (LC2i or the like, i think i used a LC5i), from that box you'll run a line to an amp that is powering your sub. From your amp you'll need some RCAs to send that amplified signal and power to the sub. When i did a 'system' in my old 2014 Tacoma i kept the stock head unit and did it this way.
Separately, you'll need power from your battery (with inline fuse) to power your equipment. I ran power from the battery (0 or 2awg if i recall) to a distribution block where i split the power, one going to the 1 channel class D sub amp and one going to my 4 channel class D speaker amp (since i also replaced all my interior speakers) and maybe power to the AudioControl box as well?... been a while, can't remember the details. I had the distribution block and sub amp under the drivers seat, and the speaker amp and AudioControl box as well as my crossovers (for door speakers/tweeters) under the passenger seat. Your amp will most likely come with a bass knob if you want to hook that up. Super simple phone type cable connection.
Since you're not doing speakers the install 'should' be more straighforward.
All my equipment was Image Dynamics except for my sub amp, which was an Alpine unit. Another thing you'll need to just make sure is your sub ohms match what your amp is or can output.