I just moved to Maine and was wondering what the exhaust laws are here. in Virginia if it came with one catalytic converter, thats all it could have, you couldn't go true dual with two cats. made no sense to me. i would really like to go true dual with an h-pipe if laws will let me.

 

I would check the DMV website check it out for sure..

I am in MA, but I believe you can put dual cats on. You just can't remove them..

 

There may be other factors that could interfer with going to a true dual. If your system uses one O2 sensor at the y-pipe, then setting it up to run well with true duals becomes more difficult. Don't get me wrong, it can be done. I think someone makes an adapter that lets you connect 2 O2 sensors into the single O2 wire, and you can also put a single O2 sensor in a crossover pipe. IMHO true duals are great for sound, but often overrated for performance. The design is great from a standpoint of exhuast flow, but flow does not always equal power. Crossovers and false duals are in some cases better, since they tend to scavenge the exhaust better at low RPM. It is really a balancing acts, since too much flow causes the the peak power outputs to increase within a narrower powerband, but a high velocity exhaust can be restrictive at high RPM.

 

i have two o2 sensors before the cat and one after. i am not sure, but it doesn't seem like that would be a big issue if i just kept the third one on the right side and had nothing on the left side.
as of right now my exhaust is set up like this: stock y-pipe into high-flow cat, then into 4 in. magnaflow muffler and 4 in. pipe out the right side before rear tire.
im thinking my idea of a 4 in. might have been overkill. sounds really good, but i think performance would be better with true dual 3 in. anyone with more knowledge please correct me if i am wrong.

 

i meant to say dual 3 in. with H-pipe would be better IMO than the setup. maybe even 2 3/4 in.

 

What size motor do you have? For a gasoline model dual 3" sounds pretty large to me. Dual 2.25" or 2.50 sounds like a better range. As mentioned by others on this forum, you need to have the correct exhaust velocity for the intended RPM range. To large and the engine will have to rev too high to acheive the correct velocity. Too small and the exhaust becomes restrictive.

 

well i just found out the laws in maine, all i have to have is at least one cat and one muffler, i can have more if i want for dual exhaust. i have a 5.4 gasser.