4g15 need a lot of work to get them up to scratch. you can turbo them up 160wkw but to get there you'll need some decent internals, springs, head work, big injectors, pump etc. then from there the ignition system hits its limits and you have to get rid of the distributor set up and move up to multi-coil with electronic control. even then, i suspect you'll hit some ceilings as i haven't seen anyone take it beyond that.
but yes, 4g15s are not rubbish at all. just takes the dedication that not many people have. most youngins get it because they're affordable. then move into something with a 4g63, rb26, sr20, 13b (you get the point) when they're ready to move on.