when you buy splits you get a woofer (bass speaker) and a tweeter...it is possible that since you ahve the tweeter you probably have the woofer in the door already...so you have splits already..might want to check first though but i'm pretty sure you already have splits if you have a tweeter. so if thats the case no you won't need any new speakers...just get a good amp...get any man...jl audio is good but you'll be spending more money on them then you would for say a coustics, jvc, jbl etc that does the same thing or better...jbls are reasonably cheap and are very good quality by experience.