Im curious to what you guys here say as many have done DP mods many times. Just doing research on all things mods and found THIS article claims a DP with a matching tune will add 40-50hp due to improved exhaust flow. Is that legit? They also say they are technically illegal, although catted won't likely draw suspicion from police if you get pulled over. So if i were to get my car inspected for licensing, will they see the aftermarket DP and fail my inspection? I wasn't planning on getting one anytime soon if at all, but who knows down the road. Just curious as to how much of the above is true.