I am in the beginning stages of modding my 03' track... and found a true dual custom HKS carbon/ ti exhaust in both 2.5" and 3" piping... i will eventually add some form of FI on the car and am wondering if i will have a loss in power if i add the 3" exhaust now... knowing that i will eventually need it after the FI is added... ????????

 

while still N/A you will definately lose some power, but IMO it will be worth it later on when you do FI, because you will REALLY regret it then if you only have 2.5" piping... just my opinion

 

We have 171 posts about “backpressure.” From those posts, do you get a sense that backpressure is needed, or that its a myth?

 

from what i can gather about backpressure, the less you have, the more "free flowing" the engine is....especially up-top. hence, you usually see better HP numbers close to redline, but you "sacarifice" TQ down low.......

 

Increased back pressure results in more midrange trq...but less trq and power up top. This decision should be easy for you. If you have any plans to run a TT setup in the near future, go straight to the 3 inch exhuast, and save yourself some money. Learn from the mistakes of those that have traveled this path before.

We are now dealers of SFR product, and offer their 3 inch true dual SS bolt on exhaust system with HKS SS Ti tip mufflers for $1595 shipped.

 

i'd go with 3inch

 

not true

 

thanks... yeah.. after just buying a new townhouse the $$$$ is limited... however i'm a MOD junky so I had to begin somewhere... for the time being... i'm probably gonna get some headers and test pipes from a friend thats getting rid of his... and run it with the 3" dual... Sharif i actually talked to you about getting that HKS true dual.. i'm the one with the friends in Team EMOTION... yeah if you can get me the SFR exhaust with HKS carbon/Ti cans i'm lookin into it... now that the REAL HKS is ridiculously backordered.. thanks for all your help guys

 

Zexy, good call, i should have said

" while still N/A, you will definately lose some power with 3" vs. 2.5" "

You'll see gains either way though

 

Not true

 

Zexy,

Why don't you elaborate instead of saying "Not True" over and over. I am anxious to hear your logic behind your "not trues'"!

 

You loose anything up top, but you may loose some trq and power in the midrange.

 

Well, if he is refering to a single 3 inch.. Power would not be lost whatsoever. To put it this in a simple way...Many aftermarket systems come with 3 single piping.

Now if we are talking about a dual for NA i'd say 2.5 would be beneficial for each outlet.

Backpressure is very overestimated/rated IMO. A more restrctive exhaust will cause added low end power and something free flow would cause more top end but too big piping would not cause power loss.

 

Zexy, so do you think for FI, a dual 2.5" or single 3" exhaust would be a better setup for the street, more low end torque, than a dual 3" exhaust? Would a single 3" exhaust like the Amuse flow enough for 400-450whp?

 

In FI applictions i'd say a Dual 2.5" or single 3" would be just fine and yes it should be enough flow for 400-450whp.

I'd say dual 3" are for extreme applications(600whp+). That's with a twin turbo setup.

 

you dun need ANY backpressure to gain torque..
So, you might ask why the hack am i losing low end torque
when i go on some larger sized exhaust like 3" ?

the reason is because your piping is too large for low
range rpm that the exhaust speed is essentially LOWER
in a larger piping.. (by simple fluid mechanics principles)
thus, the Scavenging effect for low rpm range is diminished

but yet, since you are essentially DECREASING the backpressure
with larger piping..which in turn gives you better high end horse power

P.S. rule of thumb is: backpressure requires the exhaust flow to do
WORK in pushing the flow out..so you DUN need backpressure..
but an optimal exhaust size to accomodate either high end / mid range /
low end needs

hope this helps
regards,

Godmans

 

^ Thanks for the more accurate information.

 

Actually, a 3 inch exhuast will benifit even the lower boost cars. We usually see about 15-20 whp more when running 3 inch true dual vs. 2.5 inch, at just 8psi of pressure.


The only way to answer this question, is tune/dyno the car with the 2.5 inch exhuast, and then disconnect it entirely, and see if peak whp improved. We have done this on several cars, and noted good gains on the 3 inch pipes.

Now, for instance, with a TN single kit, all you need is a single 3 inch pipe all the way back, for zero backpressure at moderate boost levels. We tested this one as well.