They sounds great on the web site ('67 GTO, 425 hp), but are there interior droning issues with the Pro V's?

http://pypesexhaust.com/sounds-gm-abody.html

Anybody using the their XChange intermediate? Do the caps on the ends of the X seem to help/hurt performance? I wonder what effect they have when the caps are on?!? Seems like it would interfere with flow (place for back pressure to happen).

http://www.pypesexhaust.com/xpipes.html

Thanks!

Andy

ls5, I'll let other members comment on the noise level of the system. I can tell you that when the caps are on the dumps, there is some turbulence created as you suspected. In tests we lost 10 hp versus having just a regular X crossover. However, for a racer, the uncapped crossover GAINED 10 hp over even open headers. So it all depends on your goals. We figured, if you need the extra power, you'll open the dumps. On the street, where you most likely won't need them, leave them closed. Of coarse if you add electric cutouts, you can have the best of both worlds. smile.gif

Ccass

Thanks for the response. I was just told about your products recently and they seem like they're top notch!

The car is in the midst of a full frame-off. It will be on the street 99.9% of the time (never say never! ;) ), we figure it'll have north of 500 hp based on the the other things we're doing to the motor, with an aggressive Lunati street cam. We really want the "lumpiness" of the cam to make its way through the exhaust system. That's why I liked the Pro V sound clip so much!

I just don't want to get a headache everytime I take it out!!

Is droning a problem on either the Pro V's or the Race Pro's?? The sound clip of the Race Pros (2.5" system) seems to pick up drone at about 4,000 rpm from outside eventhough they're not chambered??!! I always thought drone was a consequence of chambers.

Anybody have experience with either/both of these mufflers??

Thanks again!

Andy

In most cases neither the Pro-V or Flowmaster are ideal mufflers for a 500hp motor from a sheer performance standpoint. In all our tests, the 450+ motors gained hp with straight thru mufflers over chambered mufflers. All performance mufflers are going to develop some noticable resonance inside at a certain rpm level while under light acceleration (usually 1800-2500rpms). The X crossover will take away some of the resonance. Straight thru mufflers will suprisingly be a little more tame. By design, you lose a little of the raspy edge that a chambered muffler has but the resonance will be comparable between these mufflers. If the chambered sound is important and you are going to be 99% street, then go with the sound you want. You can always make the extra hp you need by opening up the dumps.

Thanks for the reply! That's very helpful and confirms some of what we've been debating here.

What about a 3" over 2.5" system? I've heard that sometimes it's better to have 3" up front, with 2.5" tails, but with this type horsepower, will we get max performance from 3" all the way back?

How much of a problem is there with rattling on a 3" system on an A body? Do you get many complaints about it?

I assume some of that depends on the skill of the installer, but do the Pypes 3" systems fit well without a lot of messing around (honestly!) on a '70 Chevelle, such that the car's stuctural interferences that might come into play with the larger diameter pipe are accounted for out of the box in the your plant's mandrel bends?

Thanks again Ccass!!

Andy

Just to close the loop, I bought the Pypes full 3" coated system with Race Pro mufflers and the Doug's coated headers they sell to go with them.

I sure hope they fit/work well!!

Thanks for the help!

Andy

Andy, I also went with a Pypes 3.0" X pipe system. I went with their "straight through" mufflers based on their recommendations for my intended use and expected power output. I haven't installed the kit yet, but the pipes look to be nicely bent and it came with a nice set of instructions.

Wes

I'd be interested in your thoughts after you get them on board. My install is months away. Just trying to spread out the cost of all this alittle!

Andy