[3000GT MR]

Originally Posted by Jeff@TopGearSolutions

On stock turbo's you are not grabbing much power out of any cat back exhaust. The weight advantage is actually a bigger power adder then anything else.

What he said.

[N8N]

single 3.5 has an area advantage at something less than 2.5" but more than 2.25"

is the boundary layer really significant in a typical automotive exhaust? Air isn't exactly super viscous...

[mave198]

Weight savings is the biggest plus with this exhaust.

My only gripe is how low it hangs. I've scraped the exhaust more than a few times and I'm only lowered on OEM sports suspension. Gonna have a shop look at it to see if they modify the exhaust to raise a inch or two.

[Dr. G]

Two perfectly straight 2.5" pipes technically flow a bit better than a single perfectly straight 3.5" pipe of the same length.

Either way, there's no direct performance gain, just a small weight saving. I would get the exhaust that sounds the best to you and just go with that.

[Jeff@TopGearSolutions]

Originally Posted by Dr. G

Two perfectly straight 2.5" pipes technically flow a bit better than a single perfectly straight 3.5" pipe of the same length.

Either way, there's no direct performance gain, just a small weight saving. I would get the exhaust that sound the best to you and just go with that.

[JC335xi]

IIRC the stock pipes are 62mm -> 2.44in in diameter so the total xsectional area of the VRSF exhaust is slightly greater than stock. It also has fewer bends and doesn't have the multiple diameter reductions that the stock pipes have. So you should see an increase in flow (maybe minimal but its there) and as others have said a significant reduction in weight.

[V8bait]

Originally Posted by N8N

single 3.5 has an area advantage at something less than 2.5" but more than 2.25"

is the boundary layer really significant in a typical automotive exhaust? Air isn't exactly super viscous...

No it's not really significant until you factor in multiple bends and high horsepower. Also, the higher the exhaust gas velocity is, the more it will matter. But yeah it's mostly trivial, the X pipes and turns screw with flow more than the boundary layer on the stock exhaust.

[Tiago@VRSF]

Time to find a new shop. AMS uses a 3" pipe with a similar muffler design and HPF used a 3.5" pipe with no muffler. They must not know what they're doing either.

[Tiago@VRSF]

Originally Posted by mave198

Weight savings is the biggest plus with this exhaust.

My only gripe is how low it hangs. I've scraped the exhaust more than a few times and I'm only lowered on OEM sports suspension. Gonna have a shop look at it to see if they modify the exhaust to raise a inch or two.

Most installers don't install the rear pipe high enough. I've correct a couple installs done by locals and it just involved loosening up the v-bands, raising the piping and re-tightening.

[MrRager]

Originally Posted by Jeff@TopGearSolutions

On stock turbo's you are not grabbing much power out of any cat back exhaust. The weight advantage is actually a bigger power adder then anything else.

this and NO dual exhaust is better for this car in comparison to what a single exhaust would be that stays a single all the way out the back. why do you think Supras have a single exhaust. also, why do you think S2000 owners put performance before looks and run a single exhaust out the back instead of a dual that the car comes with.

[N8N]

Originally Posted by MrRager

this and NO dual exhaust is better for this car in comparison to what a single exhaust would be that stays a single all the way out the back. why do you think Supras have a single exhaust. also, why do you think S2000 owners put performance before looks and run a single exhaust out the back instead of a dual that the car comes with.

I'm not sure about that - a S2000 is a 4-cyl so that's not really pertinent.

A straight six is naturally set up so that the exhaust pulses are evenly split whether you have a dual exhaust or a single, assuming the dual is split 1-2-3/4-5-6. So you can actually use a dual exhaust for scavenging effect if you set it up right. (that is, firing order is 1-5-3-6-2-4 - follow it through and you'll see what I mean. As an aside a traditional V-8 with 1-8-4-3-6-5-2-4 does NOT split nicely for 1-3-5-7 and 2-4-6-8 which is the reason for things like the "bundle of snakes" exhaust on e.g. the Ford GT40... but I digress)

Now the question is, how much of the individual pulses are left to travel back and forth through the exhaust after going through the turbos? I don't know the answer to that question but I'm guessing that the answer to that is "not much." But I'm willing to be corrected. But I suspect that this is far more applicable to a NA engine than it is to a turbo engine and that BMW stuck with a true dual exhaust out of tradition.

I love that tradition BTW - very few things sound sweeter than a NA straight six with a hot cam and a split manifold through a true dual exhaust. Well, there's always the traditional American V-8 and duals, non-optimal though it may be. And a V-12 of course... although being essentially two straight sixes hacked together, you could actually treat it as two straight sixes and run a quad exhaust... well, and I always thought that the old watercooled VW inline fours sounded good... not to mention the flat fours both VW and Porsche and let's not forget the flat six... well I guess I'm just a car whore. The only mainstream engine designs that I think sound like arse are the various flavors of V-6 and I never did warm up to the V10s either.

Tiago, please don't think I'm saying you did the wrong thing here. I have no experience with your product and so I'm really just thinking out loud here, and given that I suspect that any scavenging effect is pretty negligible on a turbo motor I don't doubt that a single mandrel bent pipe is a perfectly viable solution. (and I've had no issues with your intercooler either, although I finally just got my car running right and put the tune back in it earlier today.)

OK enough rambling from me...

[SuperBmw]

Originally Posted by Turbo Tinkerer

if I was going to go for an upgrade to go for a single 4" or dual 3" or the HKS, but not the VRSF. They said OEM would be plenty fine based on what they see, but if I were looking for a true upgrade to go for those, or to just go for something for the purpose of a nice sound only.

I don't see what's wrong with what the shop said? Everything they said is true, if you want a true upgrade those options would be better, the only reason to get a vrsf is if you liked how it sounded.

Originally Posted by turborevdboy11

Has to be muffler design..

Muffler is a shitty design, but I doubt it really has any effect with our tiny little oem turbines.

Originally Posted by Tiago@VRSF

Time to find a new shop. AMS uses a 3" pipe with a similar muffler design and HPF used a 3.5" pipe with no muffler. They must not know what they're doing either.

I think his shop was 100% correct in what they said, but you obviously have the right to be upset about it.

Originally Posted by MrRager

this and NO dual exhaust is better for this car in comparison to what a single exhaust would be that stays a single all the way out the back. why do you think Supras have a single exhaust. also, why do you think S2000 owners put performance before looks and run a single exhaust out the back instead of a dual that the car comes with.

Try fitting a large dual exhaust and then try fitting a large single exhaust and you will find out WHY people go single.

[mave198]

Originally Posted by Tiago@VRSF

Most installers don't install the rear pipe high enough. I've correct a couple installs done by locals and it just involved loosening up the v-bands, raising the piping and re-tightening.

Well hopefully this new shop does correct it or else I'm gonna have to drive up to Mass.....which I wouldnt mind the road trip

[Tiago@VRSF]

Originally Posted by SuperBmw

I don't see what's wrong with what the shop said? Everything they said is true, if you want a true upgrade those options would be better, the only reason to get a vrsf is if you liked how it sounded.

Originally Posted by SuperBmw

I think his shop was 100% correct in what they said, but you obviously have the right to be upset about it.

Nobody is upset, but I'm a big fan of facts.

In your opinion, you think this exhaust is more restrictive than the stock twin 2.25" setup? The removal of the twin rear cats as well as a super restrictive muffler design is a down grade? Lightening up the system by over 40lbs while providing a better flowing, drone free muffler design isn't a true upgrade?

Originally Posted by SuperBmw

Muffler is a shitty design, but I doubt it really has any effect with our tiny little oem turbines.

Everyone's entitled to their opinion, but our engineers opinion weighs in more for me personally.

Originally Posted by SuperBmw

Try fitting a large dual exhaust and then try fitting a large single exhaust and you will find out WHY people go single.

People don't go twin 3" like his shop suggested because that is simply too much weight/cost/space when it's clearly unnecessary.

It's well known that gains on downpipe-back exhausts on this platform are minimal at stock turbo HP numbers. Most of these gains come from the removal of the rear cats and the removal of the x-pipe.

The goal of an exhaust on a turbocharged vehicle is to remove as much back pressure as possible without sacrificing sound quality.

[3000GT MR]

The VRSF is by far the smoothest, straight forward design. I can see why some may think the muffler is restrictive. I don't think it adds any restrictions until your pushing 20+psi on aftermarket turbos. As stated before most people are running stockers. Also no one mentioned that the more piping exterior there is means cooler exhaust which means more dense restrictive flow. Unlike the intake you want to keep the exhaust gas hot. Having it all in one pipe with less exterior surface area is a key point.

[yorenceramiz]

Originally Posted by 3000GT MR

The VRSF is by far the smoothest, straight forward design. I can see why some may think the muffler is restrictive. I don't think it adds any restrictions until your pushing 20+psi on aftermarket turbos. As stated before most people are running stockers. Also no one mentioned that the more piping exterior there is means cooler exhaust which means more dense restrictive flow. Unlike the intake you want to keep the exhaust gas hot. Having it all in one pipe with less exterior surface area is a key point.

Good Points. Is this the exhaust you have on your car?
(not trying to pick a fight, just saw it on the signature)

To everyone else:
Also,is there a dyno we can see? or comparison between VRSF DP's with VRSF Exhaust vs. VRSF DP's with Stock Exhaust?
Im sure these two questions will settle this argument. lol

[3000GT MR]

Originally Posted by yorenceramiz

Good Points. Is this the exhaust you have on your car?
(not trying to pick a fight, just saw it on the signature)

To everyone else:
Also,is there a dyno we can see? or comparison between VRSF DP's with VRSF Exhaust vs. VRSF DP's with Stock Exhaust?
Im sure these two questions will settle this argument. lol

Yes and I absolutely love it. Quiet on the highway and driving around town (quiet enough that my girlfriend mentioned how quiet it was on the highway during a 6.5hr road trip) it let's you know that it's there when you get on it.

[ZROFCKSGVN]

restrictive? lol

i wanna know what kind of ganja they are smoking over there

[pwr hungry]

It looks like the tubing runs into two 90* bends at the muffler. If so, that is a horrible design aspect, and would be THE restrictive portion of this exhaust. If it, however, has a smooth split inside the muffler like the HPF exhaust, then I see no problems with it at all.

[Stucks]

Originally Posted by pwr hungry

If it, however, has a smooth split inside the muffler like the HPF exhaust, then I see no problems with it at all.

+1

[jblough99]

So can Tiago chime in on this to explain the muffler design? I too am interested in the internal design of the muffler, is it a nice smooth y that splits to the 2 exits or is it an abrupt T in the muffler to the 2 exits. I plan on picking up an exhaust this summer and the VRSF is on the top of my list. Also anyone that has a dyno to prove the performance gains on this exhaust, as previously stated catless DP's and stock exhaust vs catless DP's and VRSF exhaust. Again Tiago should chime in on this and put this to rest.

[Tiago@VRSF]

The V2 mufflers use a Y section internally that splits into two 90 degree bends.