[ECSofVirginia]

Ahhh, OK Ed I'm seeing what you're saying now. I'll volley with you.

In short...I doubt this Bradan setup makes any measurable difference compared to stock, whereas I've seen straight through x-pipes build slightly more power in comparison to stock.

Ron brought the pipes in himself, and asked if I'd install them...his interest was in fact primarily sound and not performance.

Quite often OEM exhaust systems sacrifice power gains for noise control, and I don't see that the stock 550 resonator is any exception.

X-pipes have been proven to improve horsepower in the mid-upper RPMs over true dual setups in a variety of applications and therefore the dual exhaust is not chosen over the x-pipe to accomplish this.

From what I've seen of the stock resonator, the exhaust paths don't intersect precisely enough to really influence the output and power curves. I believe the difference between stock and this Bradan setup is either zero or so minuscule it would be impossible to get a repeatable result to substantiate a gain.

[ECSofVirginia]

I just tried to take a picture of the inside of a 550 resonator for reference and it didn't come out well enough to use.

Anyways...if you look inside it there's one brief area where the two banks interact and it's much more of a "H-pipe" than a "X-pipe"...the scavenging effect of this is going to be very minimal.

If you want to come by sometime Ed, I've got a stock section and a true x-pipe I'm going to be installing. You can see the two designs side by side for a comparison.

[wetpet]

no need. I think you answered all my questions. thank you. see you around town

[jznd]

Toggie - thanks for the post and info. I'm thinking about the same mod on my 550, which also has Tubis. Do you have first gen Tubis or second gen Tubis? From the youtube video, sounds like the straight pipes gave a crisper sound, when rev'd in neutral and standing outside. Is the sound change similar when sitting inside and engine is under load when accelerating? Is there any difference when backing off the throttle?

[Toggie]

Originally Posted by jznd

Toggie - thanks for the post and info. I'm thinking about the same mod on my 550, which also has Tubis. Do you have first gen Tubis or second gen Tubis? From the youtube video, sounds like the straight pipes gave a crisper sound, when rev'd in neutral and standing outside. Is the sound change similar when sitting inside and engine is under load when accelerating? Is there any difference when backing off the throttle?

I have the second-gen tubis that say 575 on the bottom of them. Sound is similar under acceleration but obviously quieter inside the car with the windows rolled up. And, a little bit more "burble and pop" noises when backing off of throttle.

Best part is minimal droning noise at highway cruise speeds. 2500 and 3000 rpm is very quiet, 3500 rpm is slight droning noise. So, on the open highway up to about 75 mph, it is pretty quiet in the cabin.

What we need is someone to do some before & after dyno testing so that the hp and torque curves can be analyzed. My car feels as strong or stronger after the straight mid-pipes installation, but some real data to prove that would be useful.

Good luck.

[Toggie]

Originally Posted by wetpet

did you do any tuning for the new exhaust. what are the implications of removing the x over. my guess would be lost torque. any dyno runs in the future?

ron, what was the motivation to make the change. You don't tell us the instigation or the intended results. Sound only? increased hp or torque?

Bradan recently did some dyno runs on their straight mid-pipes versus the stock x-pipe on a 550 that they did quite a bit of work on in their shop.
Results were approx. a 5% improvement in both hp and torque in all segments of the RPM range.
See chart below. Blue lines are torque, red lines are hp, the higher lines are with straight mid-pipes.
So, about a 20 hp increase. These measurements are at the rear wheels (rwhp).

My 550 felt slightly stronger after putting on the pipes and had no sensation of less torque with low rpm's (which one might think would happen without the scavaging effect of the exhaust cross-over in the x-pipe).

[wetpet]

assuming swapping out the pipes is the only factor, those are pretty good numbers. of course, it could have just been the barometric pressure and humidity.