Some places would frown upon replacing the stock air box while others would not. Most would not have any problem with the cat-back, because there's no reason to.
Unfortunately, if you do an intake and a cat-back, your net gain will probably be $0 for a car that has a loud exhaust and that allows you to hear your BOV. We (most of us) frown upon such mods, because they cost you money for no gain...only to achieve sound. The method I use for modding/tuning is very inexpensive and ONLY touches on the parts that will give the most gain for the least money. It is not recommended to install an intake without a tune of some sort, such as a flash. Please don't make the same mistake that hundreds upon HUNDREDS of other Evo owners have made. Just take a long hard look at my mod list, then look at the results, and think about it. I have spent less than $1000 on my power mods, and for you to mimic the same parts would only cost you $1500 for a car that can do 12-flat (12.2 on pump). Now, I realize you want to keep the warranty. I was the same way, which is why I did a cat-back, safc, drop-in filter, mr dv, and mbc at first. When going to the dealership, I would remove the SAFC (2mins), MR DV (5mins), and MBC (30-40mins). I did that for about a year, because it allowed me to be fast when racing but warranty-safe when getting service done (cat-back/drop-in only). I eventually started getting sponsored parts and gave up on that, especially since I went the first 12 months with no reason to make any warranty claims despite no less than 30 different racing events.
Based on my experiences, I have developed what I call the Warrtalon Staged Packages (like Buschur, AMS, etc) that are strictly designed to spend the least money for the most power, but with high quality parts (not ebay stuff). For people local to me, it only costs them $1530 to purchase and install all these parts while including a custom mail-in flash. The end result puts them exactly where I am modding-wise except for my old SAFC left over from my DSM days. I don't even use it on pump gas, so it's not even an issue.
Food for thought...think about it.
Unfortunately, if you do an intake and a cat-back, your net gain will probably be $0 for a car that has a loud exhaust and that allows you to hear your BOV. We (most of us) frown upon such mods, because they cost you money for no gain...only to achieve sound. The method I use for modding/tuning is very inexpensive and ONLY touches on the parts that will give the most gain for the least money. It is not recommended to install an intake without a tune of some sort, such as a flash. Please don't make the same mistake that hundreds upon HUNDREDS of other Evo owners have made. Just take a long hard look at my mod list, then look at the results, and think about it. I have spent less than $1000 on my power mods, and for you to mimic the same parts would only cost you $1500 for a car that can do 12-flat (12.2 on pump). Now, I realize you want to keep the warranty. I was the same way, which is why I did a cat-back, safc, drop-in filter, mr dv, and mbc at first. When going to the dealership, I would remove the SAFC (2mins), MR DV (5mins), and MBC (30-40mins). I did that for about a year, because it allowed me to be fast when racing but warranty-safe when getting service done (cat-back/drop-in only). I eventually started getting sponsored parts and gave up on that, especially since I went the first 12 months with no reason to make any warranty claims despite no less than 30 different racing events.
Based on my experiences, I have developed what I call the Warrtalon Staged Packages (like Buschur, AMS, etc) that are strictly designed to spend the least money for the most power, but with high quality parts (not ebay stuff). For people local to me, it only costs them $1530 to purchase and install all these parts while including a custom mail-in flash. The end result puts them exactly where I am modding-wise except for my old SAFC left over from my DSM days. I don't even use it on pump gas, so it's not even an issue.
Food for thought...think about it.