My friend recently bought a 2002 sentra se r spec v. He wants to mod his exhaust, but the manufacturer says that they were able to get 10 more hp out of the spec v than the regulsr se has because of the exhaust. Do any of you know why this is? Should he look into modding his exhaust or spend the money elsewhere? I don't know much about the difference in the 2 exhausts so any input is appreciated. Thanks, Vinny