Greetings all,



Please I need a final verdict...

Should I go with the Mid pipe or a high flow Cat???

I don't want to loose tremendous amount of torque.

Please give me some feedback about your Mid pipe
or high flow Cat.

Thanks all

Serge
95 FD with only 33.000 km

 

4" open HKS Ti exhaust will spin the SO2's on 18x10" Volks when the 2nd turbo hits!!!!

Hold ON!!

You do need an ECU that can have an open pipe.

 

I've only seen one person show dyno's or the same car with high flow vs midpipe..yes the midpipe gave greater hp numbers...but I actually preferred the power curve of the high-flow..for whatever reason the hp and torque where better suited for everyday spiried driving.

 

I went highflow because i wouldnt want to constantly smell like gas and I dontintend to pay any fine for removing it either!

 

I posted this in your other thread, but here ya go again. I went with the Hi-Flo Cat for a few reasons:

1. State Emissions Testing. I don't have the workspace to change out the cat and mid-pipe myself everytime I need to have the car inspected.

2. Mid Pipe loses some low end power to give greater high end power. I want more low end, not highend (I don't drag).

3. Boost Creep. I didn't want to spend money or resources to help eleviate that problem that comes with mid-pipes.

Good luck with your decision.

 

Well, I have a dyno graph that plots my hi-flo cat VS. resonated midpipe, same boost setting and all other mods. With the resonated mid-pipe, my hp doesn't die off at the top end like it does with the hi-flo cat. As far as peak HP, 322 for the resonated mid-pipe at 12 psi, 316 for the hi-flo cat at 12 psi.

Tim Benton

 

I have a dp, high flow, and Apex GT exhaust (and the apex turbo) and can't pass emissions- the car runs REAL rich

 

It depends on many contributing factors.

One thing you have to take into consideration, is your exhaust, is it restrictive like a RB dual tip or more open like the N1 and are you utilizing a downpipe? If it's more open you will have boost creep. Also, what somputer system you're using(such as my M2 ECU, which won't handle a midpipe). But even the PowerFC can't fix the problem, and sometimes even porting the wastegate isn't enough.

I just recently traded my Ntech high flo for the Pettit resonated.....and let's just say, I'm looking to sell my midpipe already and go back to the high flo. My car cannot handle the excess boost. For all those who say you loose low-end with the midpipe, I'll have to disagree. I'm seeing full 13psi of boost at 2400rpms on the stock turbo's. Yeah I know it's from creep, but damn, you talk about low-end grunt!

As for people saying a midpipe stinks!?!?! Again, I'll have to disagree, it smells like gasoline and is way better than the rotten egg smell you get from the high flo. Also you can run leaded racing gas with the midpipe, and mmmm mmm damn it smells good!

The midpipe, however, is THE best power mod I've done to my car, but unfortunately it's not worth the hassle of trying to get it to work or worth a new engine.

If you've got a more "restrictive" exhaust system, go with the midpipe, but if you're running 3"DP and a 3.75"exhaust, like me....go with the high flow. You'll be happy, you won't be able to shoot flames.

If you're interested in the midpipe, I've got a Pettit resonated with not even 300 miles on it, I might be selling it soon(not sure) unless I can figure something out......I might just go with the Borla XR1 setup..........

 

just a quick question although it may seem stupid......will leaded gas mess up a resonated mid pipe just like it will mess up a cat??

 

why would you want to put a borla xr-1 if you already have a resonnated midpipe?

This setup is freeflow so i beleive it is the same thing as a midpipe, isn't it?

puma

 

I thought the XR1 was chambered or had some sort of packing material?!?!?

JoeD, I don't think it would mess it up...the resonated midpipe is just like a normal midpipe, you can stick your hand all the way through it, it's just a little fatter in the middle because they have a cheese grater design and some weird material around the outside. Unlike the hi-flo where the leaded exhaust has to flow through the honeycomb, which it wiil eventually destroy and/or clog.....

 

nope pretty sure it is a staight thru.

it is an alternative to the expensive resonated midpipe

 

Over this coming winter I am planning on adding a down pipe an a midpipe or high flo cat. I have a blitz TT exhaust Blitz sus intake and will also be adding a new ecu. What should I go with the down pipe or high flo, if I want power but still want reliability I'm still on my first engine 63,000.

 

which xr1 muffler do u use?

 

I've had both the highflow cat and MP and I must say that I noticed a huge increase in power with the MP especially at the transition. Like JeffShoots said, the tires break loose at the transition. I did notice however that I lost a little low rpm power. I don't know exactly how much cause I didn't dyno it, but I can tell that the car is less responsive at lower rpms. It takes a little longer for the power to come on, but afterwards it's a whole different planet. The main drawback is that boost creep "is" a possibility. I have a ported wastegate and still see creep some times. If you have a slightly more restrictive catback than the chances are greatly diminished. I guess once you get used to the new way that the car behaves, you won't even notice the loss in the lower rpms. The top end definitely makes up for it! I highly recommend it(with proper fuel, of course).

 

Can anyone comment on the difference in sound pressure levels between the resonated midpipe and a high flow cat? How about between a standard midpipe and a resonated midpipe?

My goal is to keep the car as quiet as possible while increasing exhaust flow. Right now I'm leaning towards a resonated midpipe and RB cat-back. If anyone can comment on that particular combination I'm all ears.

Thanks.

 

Resonated MP compared to the Ntech high flo....I don't think there was much difference in volume, even at WOT. Both are pretty damn loud

 

go with the midpipe. tree huggers will love ya!

 

I agree.

 

16 inch oval with 3 inch inlet/outlet.
About $126 at www.summitracing.com
Fits perfectly if installed at about a 15 degree angle.

Mike

 

I was running the Bonez hi-flow cat and it flows better than the stock cat with a slightly louder sound and helps power across the complete rpm band. I now have the Shane Racing stainless steel resonated MP. It is only slightly louder than the cat and increases exhaust flow so much better. Went from easy to control boost (WG was enlarged but not enough) to slight boost creep. I have since opened my WG some more. I am running non-seq with a mild ported engine and the MP gives me more low end torque with faster boost build with my system.

Those that say a MP decreases low end torque are full of BS.
Let me explain in simle terms.

Back pressure does not help a turbo engine at all. Most people confuse back pressure with exhaust flow rate. Lets make things simple even though they are not. How well a system works depends on all the componets and how they work together. The interplay of the different componenets is complex. If you have an open exhaust with 4" pipes all the way through, it might produce less power that a 3" system but not due to lower pressure. The smaller system with the higher exhaust velocity helps scavenge/pull the gases out of the turbos and opening chambers thus making room for more of the incoming fresh charge. This make more torque/power. Pressure varies at different points in the system and over time. The pressure within the exhaust system might be higher as it flows, but lower when the exhaust port opened. NA engines use this to tune so that the reflected pulse wave(pressure) is felt at the next exhaust opening as a pressure drop. You have heard of the tuned exhaust to help a certain power band width. You can't do this the same with a turbo engine because the turbo is a barrier to the reflective wave and causes it's own back pressure to the exhaust.

If the system is too small and restictive, any increase in flow will help. If the system is about optimized, an increase could hurt.

I run the MindTrain DP which is more restictive right where the bend is compared to other DP. This makes a small area near the turbos with a higher exhaust speed. I also use the HKS turbo cat- back which is only 2.75" ID with a quieter muffler.

When I was running the MT DP, Bonez cat, and PFC SS 4" cat-back, low end power was less and the exhaust noise way too loud. Now with the MT DP, SSRMP, and HKS cat-back; I have better low end power and very nice sounding exhuast.

 

cewrx7r1,

I don't think people are saying you lose low-end per say, but that the hi-flo will give better low-end power than a mid-pipe.

There was a dyno test on the net somewhere that compared a mid-pipe to a hi-flo cat. I don't know what brands were used, but it definitely showed the mid-pipe not having the same low-end power as the hi-flo. But it also show the amount of increase at the top end the mid-pipe offers over the hi-flo cat.

Not saying what you said is't true, but I would be interesting in seeing some tests that demostrate what you are saying.

 

I've seen the dyno graph comparison of the two....the high flo had about 20hp in the midrange and not as much on top.....


Well, I hate to say it, but with the setup I had: Bones DP, Ntech high-flo, GReddy Jspec exhaust, my low-end was really disappointing. I was looking forward to gaining all that power through the mid-range, but I sure didn't notice any, almost felt slower. However, high RPM's were a blast and when that second turbo came on line the rear end would always come out.

 

I had a 83 12A with stock porting and many other NA mods. The exhaust was a Rotary Engineering with headers, two presilencers, and a normal rear muffler. All straight thru except the muffler. It ran very low 15 second quarters.

After the engine was ported, even with correct fuel and timing changes, it was not faster. Why, the exhaust pulses were enterfering with each other. I removed the first presilencer and extended the length of the header pipes to where they joined together. Then I replaced the muffler with a Dynomax turbo muffler. According to the less backpressure theory, it should produce less power and be slower. No, it was about .7 seconds
faster in the quarter.

It is all about tuning so the pieces work together.