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

 

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.

 

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.

 

Interesting....I'm assuming you're referring to the PFS exhaust? So if I swap to a more restrictive cat-back (such as the HKS) then I should get more low-end power? My car is loud as ****, too.

Whaddaya think, Chuck ?

 

Rich,

It is a mute point since you are way too young to drink or drive.
When you get out of that stroller; borrow or swap with someone and test it.

Yea, it was a PFS polished SS cat-back with 4" id pipe. Was so damm noisey even at idle.

Chuck

 

Hi FLow Cat= better low end torgue, will pass tests.
Midpipe= Better top end, wont pass tests.

 

On a side note: if you plan on getting rid of your air pump as with many single turbo kits don't get a HP cat...they wont last too long.

Kelvin

 

I've gone through the Pettit SS mp and the resonated one and now have the N-tech high flow cat. Exhaust set up with n-tech downpipe and N1 duals. My opinions:

SS mp: The car became loud as ****...especially with the N1 duals.
I mean, LOUD! I did feel like I lost a bit down low but when the 2nd turbo kicked it was violent and you were flying!

SS resonated: The car was still loud as **** but less droney at wide open throttle. More or less the same performance.

Ntech High Flow: Supposedly 97-98% flow. Much quieter than the midpipes above and FEELS like more torque down low. 2nd turbo transition is more calm...seems like the power is distributed better along the power band.

I never had boost creep with the midpipes and using just a profec b.

If you want performance and don't care about noise or emissions...get the midpipe...even in a drag the added hp up high will more than make up for any loss down low.

Emissions and noise...get the high flo...still great performance with less hassle.

Thats my .02.

 

Go read http://www.randomtechnology.com/universal.html
and
http://www.houston-f-body.org/tech/exhaust/exhaust.htm

As I stated many times, back pressure does not increase low end power. It is the whole system design that is important.

If you produce more low end power with a cat than MP, that means your cat back is too large and the exhaust gas velocity is too low.

 

Go with the mid-pipe I was happy. if you still need a dp shoot me an email (wonder1and@hotmail.com). I guess it also depends on the person because when i started out I had straight through 3" into N1 Dual 4" tips, then after I went single I could barly hear myself talk inside the cabin w/ the windows up. Rich told me people were swirving off the h-way when I did a fly-by @ WOT. :p To solve this problem I decided to put a Fosgate 10"HE in my trunk so i couldnt here the exhaust except for when flipping channels.
Anyway go midpipe.
Happy Rotoring,
Ryker

 

If your going with the midpipe what other mods should you have?

 

im kinda in the same position''

i have an 94 AUTO FD with 48k miles

with...
PFS Purple
Pettit SS DP
Blitz NurSpec catback
M2 cold air (coming soon)

What should i go with..Resognated Mp, high-flo
or just a plain midpipe. My car sounds nice now,
the blitz exhaust gives a racey sound(not ricey)
and wanna get the cat out

What do u guys suggest?

I appreciate the help.
thanx

 

My first exaust (and present) was a DP, MP, and gutted stock cat back. Yeah, i know what you're sayin. Cheap bastard... But to be honest, it sounds pretty good. Not to loud at idle, or cruising. Under full throttle, it sounds like a sports car, not a vacuum cleaner on crack.

For awhile i had a SS DP, SS MP, and N1 Dual. The car made awesome power, but was kinda Honda sounding. Not to mention, just like everyone else says. It was loud as hell. I maybe drove 5 miles at the most with it. I sold it to Colbalt on the forum, and swaped to my Gutted cat back. I did pick up about 1psi of boost with the N1, though.

If i where you, go with the resonated or normal mid pipe. I think i picked mine up for $120 on a GB awhile ago. When its time to smog, spend the 30 mins. and put the stocker back on. CJ

 

go with a resonated mp.