LOL you could probably pull into one of the shops over here with no cats, straight pipes, lopey cam, loud as fuck, while being followed by a cloud of blue smoke and these goobers will probably pass it.


Of course, I say this now. Next year I might find myself bolting my stock parts back on so I can pass.

go over to bossmustangsonline.com and order you some of these --> http://bossmustangsonline.com/index.php?topic=3663.0

I talked with the guy that makes them, and he suggested a 1/2" or 5/8" opening to be used with cat deletes, since the sound is increased. Listen to the videos they have, and you should be able to make up your mind.

GT500 mufflers sound great with the Boss midpipe setup, btw.

That was the direction I was headed. I was going to drill out the restrictor plates to about 1/2" and put them back in after the cat deletes. The ones that came with the H-Pipe look like they have about a 1/4" hole in them. I was going to start around 3/8" and work my way up. The restrictor plate might be too thin gauged to drill a bigger hole and not have any rattling. This is a good option. The GT500 mufflers are the ones I keep going back to when I'm shopping around.

I just went ahead and purchased the 5/8" plates from BOM, so hopefully I don't want to go smaller...lol. If I do, then I will have to order new plates, or I can drill out the block off plates I have. lol

I forgot about the block off plates. I bet they are still in the Box with my stock H-Pipe. I can take them to work and but them on the drill press and try that first.

I thought Texas had a law indicating you can't run a car without mufflers. Of course with the side pipes installed you still technically HAVE mufflers- but a lot of the exhaust is just routed around it.

Also (perhaps a stupid question), do the Boss pipes bypass the cats- or are they behind the cats? Reason for question is if they are before the cats what happens if they decide to check the emissions at the side pipes?

I know I'm going to end up getting the Boss pipes- soon. I'll probably install the restrictors- but drill them out to 5/8". They sound just so perfect, IMO.

BTW, in a discussion of this on another site, I saw where Ford Racing did dyno testing on the Boss quad system and- with the restrictor plates removed- the HP difference was +6 to +7 hp. Not much, but considering the Ford Racing tune supposedly adds +16hp, that would be 420+16+7= 443 (awfully close to that 444hp number for the stock Boss 302 :^).

They exit the midpipe after the H crossover, so after the cats.

As far as laws for mufflers, some places enforce noise ordinances more than others, but a lot of people in Texas run muffler deletes/straight pipes.

Also, the typical drive thru type inspection place doesn't have lifts, so on a Mustang, they won't make the effort to visually inspect the exhaust system for the retention of cats. As long as your tune is okay, pretty sure you will pass the tail pipe sniffer.