So i'm researching the different types of exhausts, and I want to avoid having back pressure problems. In my opinion if you are going to be buying something that makes that nice noise we all want... it should also make your car perform better. I've been plagued with all these choices and nice sounds from these exhausts only to see some dyno sheets from a few... to have a big loss of power in the low torque area. Right now I am completly stock but will do the cold air intake, and may do supercharging in the next year if I still love the Z as much as I do now. I also want to do headers but all these high flow huge diameter tubes make me wonder just how much back pressure I will be losing. Right now the exhaust that seams to fit my need is the Borla. The tubes are not 3" or 2.75" which should make no torque loss, but an improvement. I have heard from some tuners that installing headers may make your engine run lean at high rpms and that could be VERY bad as you know. Also as far as pairs of exhausts/headers... the NISMO and Borla are the only two I would probably go with. Just with exhaust first..are there any other exhausts besides Borla that give + gains throughout the whole powerband? Will the exhaust/header combo make + gains throughout the powerband or am I going to see a torque loss? From a performance standpoint, are there reasons to go with a single over a dual besides weight? There are too many posts about how exhausts sound, and not enough posts about how they really make your car go, or not go.

 

Because the stock exhaust is not horrible, aftermarket systems don't show the gains that systems show on other cars, same goes for headers and test pipes. I am not saying gains are not there but the dollar per hp is steep with the Z. So most here have decided that if it is between 9hp from one brand and 10hp from another, looks and sound become more important in deciding. I guaranty if someone sold an ugly exhaust that delivered 30hp, it would be a top seller.

If you are truly thinking about going FI, I would look at what those people are doing because each type of FI works better with different setups.

Chris

 

Back pressure is a myth. If back pressure is good, then more would be better. We would all have 1-inch exhausts.

The single vs dual exhaust performance debate continues. The question is not single or dual, the question is potential volume. One of our members calculated volume for single and dual exhaust of various diameters. Good read.

I recommend that you:

a. Set a budget.
b. Decide what configuration is best for you. Single. Dual. One or two mufflers.
c. Listen before buying.

 

Of course too much back pressure is not going to help you. That's why restrictive stock exhausts are swapped for free flowing exhausts. Too much free flowing is not good either...

a) ~1,500
b) and c) Does not really matter. I want performance, sound is somewhat not important. Any good quality exhaust is going to sound good. I like the look of dual, and the look of single. I am not really picky, yet I have one big requirement. I don't want low end power loss.

 

A free flowing exhaust is what you WANT. The backpressure myth probalby started so people can sell poor header collectors and still make money with the back pressure effect. With a good header collectors, longer duration cams, a free flowing exhaust is NEEDED. So heres what I suggest for thet Z: X pipe, dual 2.25 or dual 2.5'' exhaust. This will likely mean a custom exhaust setup since very few manufacturers sell an X pipe exhaust.
Why? Cause its expensive to manufacture. Stillen sell it, and it makes good power. Its a little heavier than stock but who cares, its low to the ground (effetively giveing the car a better center of mass), and its got much more piping than stock so the weight is atleast deserved.

 

I read on this site, I can go back and check through the hundreds of posts.. but someone putting a three inch catback exhaust noticed a drop in acceleration power. Back when I had my tahoe I put a flowmaster exhaust on it with 3 inch piping... and experienced the SAME problem. I also put a K & N air filter on the truck and with both mods combined... I had near zero acceleration power. I put the stock exhaust and stock air box back on the truck.. and voila I had my torque back. I am somewhat confused/want to know more about correct pipe sizing needed for the horsepower the car has stock to notice the most gains. I am sure if I did alot of engine work to my tahoe back then... the larger diameter piping would of benefited me throughout the powerband, but in the case I had no mods besides those and had a huge loss. I hope this is making sense.

 

The backpressure myth was created by people who did not know about the velocity and scavenging effects and just assumed that it was backpressure that helped torque.

SCC has a great article about it here
http://www.sportcompactcarweb.com/te...haust_systems/

You need to plan your system purchase around what you plan on doing with the rest of the power plant. If you are going FI, you need a system that works well with that, if you are staying NA, they you need something for that. It is all about getting the right system for the job.

Chris

 

high exhaust velocity = good
backpressure = bad

wide open exhaust = LOW exhaust velocity
tiny exhaust opening = backpressure

Therefore,
The best exhaust would have very little to no backpressure with an OPTIMUM diameter

 

Great article... I scimmed through it before, but I can sit down now and really pick it apart. Thanks for that!

 

hmmmmm....since I am still new as well, the best advice is do your own research and don't let something one person has told you affect your decision. HP gains for exhaust are gonna be all within 2-3 which is unnoticeable unless you dyno before and after every mod you perform.
But I think davidv said it best...

I recommend that you:

a. Set a budget.
b. Decide what configuration is best for you. Single. Dual. One or two mufflers.
c. Listen before buying.

 

HAHA... that sounds oddly familar. Sounds like something Davidv would say.

 

So let me ask this...I have been told a couple of different things about a TT setup. On one hand I have been told that for the turbos it is good to have some backpressure...i.e. not just straight pipes, some sort of mufflers....
On the other hand I have been told that absolutley no backpressure is what you want.

 

the output of a turbine is proportional to the difference in pressure before and after the turbine. If there is backpressure there is less power output.

Anyone who says you need backpressure for ANY reason:

1. Doesn't even know what they mean by backpressure
2. Is repeating something they heard from somewhere


If you're confused I suggest you read my post a few posts up

 

I did read your post, and I was not debating the power output part of the equation. What I was told is that, and I will not get this exactly right, the turbos need a little backpressure to keep the seals from leaking.
Now I will be the first to admit that I am not a mechanic and do not know all of these things. But, it kinda made sense, but then when I think about it more, why would the rubos need pressure to keep them reliable?

 

So what did you order?

 

Who?

 

ceddyluv82. The member who is searching for an exhaust system.

 

I am leaning towards the Borla because it seams to be a well made and put together system. I had it on my MINI and noticed an improvement throughout the powerband. I also like the Topseed N1 exhaust because I really like the sound it makes the Z have. I just think with the Topspeed N1 I am going to suffer alot of torque loss.

Topspeed

Borla

 

If you ask me the topspeed is a bad design for N/A. At least it's not the optimal design

 

Independent testing shows horsepower and torque gains for the Borla. Go for it.