I'd say no because if you get caught you will get banned (I like my name, Safinn) and you won't be able to go online which is what I mostly do.
There is no proper chip for the 360 that will do anymore than assist you in flashing your DVD drives firmware or give you the same end result. I’m going to say no, if you flash your 360 it will get banned from live at some point, to me live is the best thing about the 360 and I wouldn’t want to lose the ability to use it. If you still have a warranty for your console that’s also gone so unless you can swap it for another in a shop you will end up needing a new console if you get an RROD. The only advantage to flashing a 360 is you could get retail games for next to nothing or play a few games that leak early like Gears 2 did, there’s no Xbox Media Centre, Emulators or anything like there was for the Xbox 1.
So really all you get is the games ceaper, sometimes earlier and can only play the single player and when you have completed that what do you do then? Go over the missions again? It would get very boring without xbox live.
The best thing you could do to 'mod' your Xbox360 is to flash and use a hacked firmware on the console's disc drive. But really, as said above this won't give that advantage of playing/using homebrew games and software like on original Xbox or PSP systems. Only good thing is that you could easely play the games you'd like to play, but don't want to pay a full price for, right at the moment when they come out, or even earlier. Your ID/profile/gamertag will never get banned, but your 'flashed' console is likely to get banned whenever Microsoft does another check. I know just one guy who is using the same hacked Xbox360 on Live for more than 2 years without a ban, but with the price of visiting sites like Xbox-Scene constantly to know when to plug out that internet cable to prevent to be checked (plus reflashing the drive with updated firmware).. Really, if you'd prefer pirated games, the PC is a much better option as it's suffering from it more than ever, making most new games almost protection free..