Originally Posted by AmericanBulldog
what would happen if i don't? the one i want says a tuner is required but doesn't say exactly why.
The Hpipe you're looking at, does it not have catalytic converters? If it doesn't, than the rear O2 sensors will throw a CEL. You'll need a tuner to disable the CEL for any catless mid-pipe, whether it's an X or H or anything.
Hope this helps clarify things!