yes there is tdo4 is the smallest then tdo4l then tdo4hl there is a few diferent sizes indeed but there not that far off each other
i personaly prefer a tdo5 on a 4efte it comes a bit later on boost but pulls A LOT HARDER on boost :)
i think weprs kits are best value for money he has some nice kiits for 400£ and under delivered and lifetime waranty
you could also buy the toyosports tdo4 mani/downpipe in mild steel they are good and work wel just weld some braces to them and they last wel there 180£ +-
i have 1 off those atm with external welded on and made adaptor plate to fit my stock cat so i can pas nct/mot :) i am the first to do so !!!