my06tc

iTrader: (2)

ok this is and odd question but i get ask alot concering the most restrictive part on the exhaust on the TC......we all know that the header is pretty restrictive cause it has the cat on it and doesnt have it on chambers for the cylinders.....after much research on this partcular item im finding that the downpipe on the tc is more resrtictive then the header cause theres lots of uneven bends different size piping......Nowim not saying this is true but most people i talked to and mechanics they never saw a crappier dowenpipe like the stock one of the tc it makes a little different when replace with and aftermarkt one but nothing real noticeable but if you change the header nit only will it sound like crap with you will notcied alot more power.......

Let me get you gies opions on this to help better understand if this is true or not or is it even worth changing the downpipe i only did it cause honestly the stock one look like crap just didnt like all those crappy bends two different size pipes welded...just my 02 sense..

let get some thoughts..

tcCALI

what is the question exactly?

GammaTNT

iTrader: (8)

he want to know if it is worth the money to install a aftermarket downpipe(aka, the S-pipe)

i installed the DC header and Invidia s pipe at the same time, so i can't really tell you.

kphyle22

haha i kinda thought the same thing.

but I think he's asking:

Since the downpipe is so bent and restrictive, is it worth getting an aftermarket one that is less so.

maybe, sorry if thats not what you were asking..

IMO, I don't think exhaust is the biggest power issue. I think for our engines, a 2.25 pipe no matter how bent is plenty sufficient if not oversized. (Unless you're turboed)

rrimportracer

the s pipe is the most restrictive part of our exhausts

the pipe has a lot of bends and it gets smaller around the bends i think its like 1.75 around the bends not 2.25

captainlaziness

Yes, loud and raspy. No, you won't notice a lot more power because it won't yield a lot more power.

kphyle22

yea. it was wierd. when I installed my header, it actually made things quieter. I had my CAI in, and it seemed to take that away and just replace everything with a crappier rasp.

(thats why I have an HKS hi [ower axleback and a resonator for the midpipe on the way) yay!

2fast4you

I replaced my s-pipe [downpipe] and continued to use the stock manifold... there was no noticeable difference in power if that's what you are asking, my06tc. Yes, it is a restriction, but not enough to severely affect performance. It seems that the bigger problem lies behind the s-pipe with the second cat and muffler... but that mostly based on my own anecdotal experience.

chicotunner07

i didnt notice any power increase, but i did gain what seemed better throttle response, and some increase in exhaust sound, this was with megan oe-rs exhaust and mid pipe, with ebay spipe with crappy fitment

i now have agency power catback with invidia spipe, honestly, its not really worth it if your gonna pay retail, get one used if you can, i paid 100 shipped for mine, good luck

my06tc

iTrader: (2)

bascially i was asking is the downpipe or aka (s-pipe) more restrictive then the header is...when i installed my invidia downpipe i notcied the exhaust got a little deeper slighty better throttle response probably 1-2 horse gain even at that..thinknig about getting a header but thats awhole nothing thread..when i tell people about the downpipe they think its a piece of pipe connected to the header most dont know about the bends..i didt relized how bad it was until i actually had it out..dont know never seen anything like that before

senseiturtle

If I HAD to rank them... most to least restrictive.

1) S-pipe
2) Header (since it has a cat).
3) Mid-pipe (since it has another cat).
4) Axleback.

The Spipe wins as most restrictive, since it's the only point where there's an actual reduction in flow radius. Mathematically, reducing the radius increases the resistance by a power of 4... so a drop of of 1/2inch only allows 1/16th the flow at maximum velocity.

Of course, this is oversimplified, and doesn't take into account a lot of complicated engine dynamics. In short, too large of a pipe is self-defeating (see axleback below), but better too large than too small. Airflow in our exhausts is never at maximum, as in, even our stock exhausts can easily handle all the air the motor can put out.... just not "ideally."

The next 2 are the cats, since they increase resistance to internal flow... but at the same time, diameter slightly increases, which offsets some of it. Resistance in the airway itself isn't raised to the power of 4 like diameter is, but it's certainly correlational. Double the resistance, half the flow.

Finally, the axleback is the least restrictive. This is an example of having too much diameter at any one part, which leads to a cooling of gasses within the muffler, increasing resistance slightly.

---

"Crush" bends do impact flow, but is largely irrelevant unless it drastically decreases flow radius. Most of the time, it doesn't decrease it appreciably. There is some asthetic quality issues though.

The ideal exhaust would be just big enough to evacuate all gasses, at minimum loss of exhaust gas temperature, over the shortest distance, and zero reductions in flow diameter.

For us, that happens around 2.25 - 2.5 inches. Above that, gasses cool too rapidly, and it becomes self-defeating. 2.25 inches is plenty of flow radius to handle everything an NA 4-banger can dish out, and more.

Lester4

I installed the Invidia S Pipe /without a header. All I have is an intake and axle back and I could tell a bit of difference. It is for sure worth it IMO.