at least you are not putting pnp kit on a reflector... retrofitting purpose is for lighting improvement having more usable light and some styling.. i have retro'ed a few including mine, it is also better to search and read through hidplanet.com if you want to learn more as i have learnt a lot from there..
retrofitting is not just plug and play.. you have to consider a few things
like components and how would you want your headlight to look like.. w/c includes..
1. projectors- (optics used to distribute/project the light emitted by the bulb) which would be better, which is best, they are categorized with with bi-xenon (hi and low beam in one), low beam only, high beam only..
available with oem's, replicas, and chinese aftermarket..
2. hid bulbs- oem are expensive but worth it....
3. halos/led eye-lines.. adds to llok and use of DRL
4. ballasts- oem/chinese aftermarket.
5. wirings
6 painting
this is my uncles 04 sorento waiting for some halos to attach to painted
this set-up has
lowbeam- hella e55 projectors (oem) more distance light than width (bi-xenon)
high beam- Mini H1 (chinese aftermarket) basic projector good width but distance sucks, just used for looks (bi-xenon)
here's mine...
again, search some stuff first on what you will need, you will spend less and choose better stuff depending on your choices..
oem products are always the best but then again cost is your problem
replicas are 2nd and chinese aftermarket are value stuff...
hope this helps