so far Erebuni has responded very quickly with emails, here is what I got so far:
ME:
Hey,
I recently bought a erebuni kit from you guys, for my 2002 mazda protege5, the 123B series, that comes with sideskirts and a rear apron. I had to make only minor modifications to get the sideskirts to fit, but apparently you have to drastically modify the stock rear bumper on my car to fit the erebuni bumper, do you guys have any information on what kind of mods? Like, do I chop the bumper in half, or what? I'd appreciate and customer service you can give me, thanks.
Reagen
THEM:
The bottom section of your factory bumper cover will prevent you from installing our RA therefore you need to cut the parts of the lower section of your cover that interfere with the installation of our RA. Then you need to bond on our RA onto your bumper using epoxy and screws. If you have any further questions please contact our tech department at the number below.
ME:
well I test fitted the erebuni rear apron over my stock bumper and it ended up looking like it was 4-5" too short on one side to reach the fender well area. I'm not about to cut the bottom half of my bumper off until I know it will fit just right.
THEM:
Please e-mail us a picture of our RA up against your rear bumpr so we can see what you are talking about. As you know this kit is made for the Japan spec Mazda 323 which has different bumpers then the Portege 5 however our customers in the past have been able to install our RA on their Protege 5 bumper by cutting the bottom section of their bumper cover. We don't have first hand knowledge in that, we are just passing on to you information that we have from past customers. We would also not want you to do anything to the RA if you think you can not do it, since you can not return the RA if you do anything to it. Please include your phone number with the next e-mail that would have the pictures and someone from our tech department will call you back. For any further info please contact our tech department at the number below.