i have a le k/c 4x4 that comes with the rf system.

i find that it is pretty wimpy with the deep bass in some of my music.

i'd like to get some better quality low end sounds out of my system.

what's the most cost efficient way to do this? would a new sub do it? or do i need to buy more, like amps, deck, sub, etc...

at most i'm thinking amp and sub?

also, how big is the sub under my seat?

I bought new stuff, but I ran all my speakers straight through the amp(300w) and with some RCA cables connected the amp to the aftermarket stereo, you can turn it all the way up and I don't hear a crack. I also connected a sub on that amp. Sound awesome!

ya i stopped buy 2 audio shops in my town and talked to the guys to see what was involved.

basically, all i wanted to do was put in a better/bigger subwoofer. and if i had to, a new amp for the sub.

but apparently it's a huge undertaking to do. they said they can't just wire things up to the RF factory system.

said they would have to bypass all hte existing wiring.

are they right in all this or do they just suck?

Well it works better when they re-wire the entire system but it's not 100% needed. Especially if you can live with your curent highs. Just get a 2-channel amp with some low ohms and some fair wattage. Wouldn't be too much just to do this. Make sure the amp is bridgeable to get more out of it.

Maybe something like this will work for you.
http://www.pac-audio.com/oem1kits/oem1search.htm