Stopped by a highly regarded shop today about a catback for my '05 base with the hahn stage II. They put the car up on the lift and said that the downpipe hangs too low and they would move it up in the tunnel more. I said I'd like to at least get 2.5 from the downpipe back. They looked at it and said they wouldn't go any bigger than 2.25. I was under the impression that with turbo exhaust bigger is better. To a certain point. He said with 2.5 I'd be losing back pressure and low end. You think they just didn't want to take the time to fit 2.5? Or are they right? They do mandrel and really high quality stuff so I surprised when they told me to go with such small piping. Not sure what I wanna do, it's gonna be a $500 trip if I do it. But for that kind of money I want 2.5 minimum.
I have access to a hoist and a welder at my dads shop so that's what I was gonna do. The mandrelexhaustsystem kits look pretty good. I was thinkin about the 2.5 one cause I'm lowered on sportlines and don't think I can clear the 3" without allot of extra fabbing.
Back pressure is restriction... Restriction is bad. On a turbo car, larger exhaust typically equals quicker spool times
That's what I thought too and he said that yes you will make up for it in top end but you'll lose out down low. Then he tried to tell me the downpipe was 2.5 but I'm pretty sure it's 2.25 that comes from hahn. I could be wrong tho
3inch can be done lowered.
2.5 should be fine unless your going to all the records.
FU Tuning
I may or may not ever up the boost from the standard 8psi. If I do, 2.5 should still be good I would think. Right? 3" right now with stock motor and the hahn stage II would be a little overkill wouldn't it? Maybe I'm wrong, I'd like to do 3"
what he saw was a narrow path for the pipe to fit.
what he saw was easier work with smaller diameter piping.
what he was trying to do was sell you on stuff that's easy for him to do so he can maximize his profit.
simple.
more is more. less is less. especially when boosted.
back pressure = bs.
Man I'm so tired of that "backpressure is needed" myth on turbo cars... hear it at least once every month at local tuner meets. SMH.
Scorpio1 (James K.) wrote:Man I'm so tired of that "backpressure is needed" myth on turbo cars... hear it at least once every month at local tuner meets. SMH.
I'm so tired of it on any car. Scavenging effect and exhaust gas velocity have nothing to do with backpressure.
"In Oldskool we trust"
Amen, it just urks me that this is not common place knowledge in this age of so many modded cars running around, and it really bugs me the idiots spouting this @!#$ locally are the Turbo equipped Hondas, Nissans, and a even few V8 guys.
I'm standing there each weekend night like, "How has your cars motor not blown up yet?"
Just throwing out a random idea here for exhaust. What if I kept the 2.25" o2 housing then from there bolted to a custom made 2.5" downpipe then bolted to 3" all the way back. This would be cat less of course. Would this flow good? Or should I just do 3" from the turbo back? Or a 2.5 do to 3" catback?
The exhaust will only flow as much as the smallest diameter will allow. Personally i would stick to either 2.5" or 3" from the turbo back.
also your boost time will also be determine by your tune.
btw, what do you guys use to tune? ( i have been out of this site in like forever lol)
Hp Tuners is still what people are using unless going with a stand alone system as far as I know. Tell Carlos Dave said hi, I haven't been in south Florida for awhile.
