LALEX1

iTrader: (22)

Has anybody actually dynoed their car before and after to see what the actual gains are?

bcsc400

iTrader: (1)

Look at post #397

LALEX1

iTrader: (22)

Thanks. I think I have seen that post. I was actually looking for a back to back dyno with only a headers upgrade.

JBrady

I had bought a Top Speed 2.5" straight resonator but internally it necked down and had sharp edges so it is not a true 2.5" part. I sent it back. I recommend Magnaflow, Dynomax, Borla or any part that uses a true 2.5" internal design without sharp edges.

Below are pics of the TS 2.5" that I returned.
Look carefully and you can see that at each end the internal pipe size squeezes down to less than 2.15" and the perforated core that is roughly 2.5" is capped at each end by the squeezed down ends (swaged). On the inlet side this is not that big of a deal other than a slight restriction but on the outlet side a sharp "lip" is created that creates more of a restriction by inducing turbulence as well as being physically smaller.
Keep in mind that the a pipe with an Outside Diameter (OD) of 2.5" will have an Inside Diameter (ID) of roughtly 2.37" so that is your ID starting point.
The stock 60mm pipe (2.37" OD) is roughly 2.14" ID (pipe wall thickness for 16 gauge is .065" x 2 = .130" total wall thickness to be deducted from the OD size.

So, a true 16 gauge 2.5" OD tube has an ID size of 2.37".
The factory 60mm OD tube (2.37" = 60mm) is roughly 2.13" ID.
The Top Speed part has the same ID as the stock tube but with less desireable internal aerodynamics.

BTW, the stock resonators on the GS4xx are actually slightly larger inside than the pipes that feed them! Another reason to KEEP the factory parts that work.

vwynn

iTrader: (4)

dammit.. i left all 6 resonators (yes 6.. i had 2 stock cat backs lol) at the exhaust shop

johngoldsc

20 hp for the 1uz sounds good

HtownGS4

iTrader: (1)

Just installed my PPE headers on my 98 GS400. First put them on with the factory cats, and 2.5" pipes all the way back (and an x-pipe after the cats). Waaaayyyyy too loud! And seemed to not get much power from them. Went back to the shop and had them reinstall the factory resonators. Wow is all I can say. The car sounds much better now, and I can actually feel an increase in power. Especially through a wider portion of the power band. Need to get it on a dyno to see some real #'s. Though I plan on doing a cold air and an ECU that can be tuned (will be installing cams soon after so I need the tuning for sure). Great buy!!

spdrcr771

iTrader: (21)

Sweet, when you say, you had them reinstall the factory resonators, you meen they put the stock Y pipe & everything back on or just the resonators & stock mufflers. Also very interested in what stage & brand of cams you are going with & tuneable ECU. Dyno now so we can see how much tune & performance you get out of the cams & ecu. Lextreme's stage 2 cams are reported to add 31whp to our motors.

bcsc400

iTrader: (1)

I used a Vibrant ultra quiet resonator. It's built with a true straight through core. It also eliminates any drone or rasp and is very well made.
http://vibrantperformance.com/catalo...products_id=46

sakataj

iTrader: (182)

can u run the stage 2's on OEM valves/springs/retainers or just the stage ones (can you even run the stage ones on OEM?) do you happen to know power level of the stage 1's?

http://www.lextreme.com/Lexus-Toyota-cams.html

vwynn

iTrader: (4)

you getting cams Brian??!?!

spdrcr771

iTrader: (21)

Yes on the OEM valves. Im not sure on the springs part. But then again, if im already there & im "upgrading". Im changing the springs too. Dont know anything about the stage 1's. I heard the stage 2's on a you tube video, & its not like it was lopping like a big block chevy & idling rough. So why even thing about the stage 1's.

sam430

iTrader: (10)

Nice! would be nice if there were a couple of flex joints to make the install easier.

sam430

iTrader: (10)

Where did you get the 31whp number from?

sakataj

iTrader: (182)

i kind of gave up on the idea of the cams/springs/retainers as the cost i can put in a ls2/ls3 and make that kind of power i would be making....

im gonna dyno in the next week or two BEFORE my header install on some fresh plugs and then again after the header install....looking forward to some #'s