Does anyone know of modifications that can be applied to your standard bass to improve the sound quality? Or has anyone modded theirs? I know of after market pickups but getting them to fit comes to mind.

Thoughts, suggestions:

all depends on what type of sound you're going for... if you're just looking to clean up the sound you'd be amazed at what new cables and batteries in your pedals can do...

personally i've switched to flat wound strings... makes the sound a lot smoother and bassier (costs about twice as much as normal strings though)... i'm alos debating on ripping the frets out (a la jaco pastorius) but i've only got the one bass for now so i don't think i'll be doing that anytime soon...

Wow, fretless is a whole new ball game.
I havnt got any pedals as yet, im wanting an overdrive. My cable is pretty new. I just want my own sort of unique bass with better sound quality that standard.

that's totally where i want to go... hehehe... and i've played a fretless before so i know what to expect when i take the plunge... i figure i'll end up buying a 5 string fretted and converting my 4 string...

and for pedals on a budget captain... i'd say a volume after the overdrive... you can really add a lot of oomph to your sound and style with that...

Im going to hopefully get a decent amp before i start messing with my Bass, which is a Ibanez GSR200 (Novice Bass) 4 string. dont particulary like it - but hey, its a Bass innit. Thats why i wanted to customise the pickups just so i can keep it abit longer as im gonna be spending money on a Hartke Bass combi item. I eventually want a Fender 60's Jazz bass in sunburst, mmmm.