there were 2 sets of wires on my back 6x9s that one was for the bass that worked with the gain slider and one was for higer notes. If you tap into the lower one it wont be that bad. yah I know that it will not be amazing but neither is anything else unless you upgrade everything. If you wanna try it go for it. Just saying for a stock hu the system wasnt really bad. If it has bass blockers in the line you can just cut those out too. The way I have installed them in cars they didnt sound bad like you guys are saying. I have a friend i wired up with 2 MTX 9500s and the second largest amp MTX makes and he has a stock headunit for now because he wants to get a good hu and doesnt want to buy a cheap one now since he spent all his money. It was really good, not the best but it gets the job done if you need a fix for now, or dont need perfect quality.
1994 SSE, 180 t-stat, gucci accented interior, suede headliner, eclipse avx5000 headunit, two 7.8" sunvisor screens, two 7" headrest screens, dvd player / tv tuner, infinity kappa perfect 5.1 components, infinity 12.1 perfect in the trunk, 2 rockford fosgate 350s powers, infinity refrence 7541a, 0 gauge audiobahn high flow wiring, duralast gold battery, sound dampened trunk and doors, xenon-white headlights, 2 15" and 1 20" red neons shine on the back doors, 2 3" and 6 12" blacklights lighting up the whole interior, red leds in the vents, red optx el neon pedals, red streetglow headlight leds, clear corners, pilot seven color angel eyes, blaze seven color underlighting kit, viper 791 xv.