Dirk, An H pipe in a car with a cruciform frame (63 - 65 Riviera) might be a challenge. Your frame forms an X right where you want your pipes to form an H. Good luck and let us know how you come out.
How are you going to fit an H pipe in? There is barely room to get the headpipes around the frame and I had to notch my lower spash sheilds on both sides to clear. After you clear the frame rails you have the center tunnel in the way and you don't really get a clear shot from one to another till your back at the rear axle.
If you open the link to Sanderson's, the promo reads for Rivieras. From the pictures, it looks as if they took pictures of the same ones that TA is selling. Hmmmm? Wonder who is farming out production to whom? Perhaps both are the same product made by a third party; or perhaps they're made by Sanderson and distributed through TA; any number of possibilities. We probably won't know until someone compares them side by side.o No: I was at the Good Guys event at the Kansas Speedway last weekend and talked to one of the techs at the Flowmaster trailer. He told me that if you use the transverse crossflow muffler, there's not that big of a need for an H pipe. The only muffler they sell that will work on the 63 - 65 Rivs in its original space is their dual inlet / dual outlet muffler, part #42582 in their 80 series. It has 2.5" inlet and outlet pipes. It's only 24" long overall so it will need some additional pipe work at the back end of the exhaust pipe and the front end of the tail pipe. It's a pretty aggressive sounding muffler; the tech suggested a baffle between it and the passenger compartment or a pair of resonators where the OEM resonatos were.
the tech guy at the garage where the engine and transmission are being "overhauled" showed me that the only place to put an H-pipe or even X-pipe would be in front of the rear differential (my exhaust pipes are routed to come out in front of the rear wheels) . these type of exhaust pipe connection are done best at the front of the complete exhaust system. this would mean to connect L and R pipe just after the collector reducer of the headers ... but there is no room for that. i will either skip the "H or X" pipe idea or think of another solution. let's keep fingers crossed that i can post pictures some day. BTW i am running with only 2 big flowmaster mufflers (1 for each side) and the car has a great growling V8 sound ... but luckly for neighbours it's not annoying.
I doubt you're going to see much gains if any by putting an H or an X that far back. If you still want to go with a cross internally in the muffler. Magnaflow sells one with a dual in dual out and it has an X pipe in it. I was looking at them back when I was thinking about trying to put duals on my 4th gen trans am. To realize the true benefits of an h or an x pipe they must be farther upstream in the exhaust system. An old rule of thumb on positioning was to spray some spray paint strips down the pipes. Where the paint stopped burning off was where you put the H pipe. But I agree with people here that the Riviera doesn't leave much room to put one in.
