I just got my IS350 a couple of weeks ago. I came from a 600hp 335i so obviously the power is definitely lacking. I already added the F-sport intake which makes a nice engine noise but I did not notice much of a difference power. I have been doing some research and see that the PPE headers seem to give the most power. I would like to get these but i don't want a full exhaust as I don't want the car to sound really fast when it is not. I just want a a little more power in the mid range and top end for myself just when I feel like powering out of some turns. So now the question is has anyone installed the headers and kept the stock exhaust? I assume the gains will not be as great but I was also thinking about adding a midpipe. If I can get another 10-15whp from these mods I would be happy.

P.S. WTF Lexus! They offer the slower IS250 in a manual and not the IS350!

 

If you're already removing all 4 cats (which is what headers and a midpipe would do) you might as well put an axle back on instead of the stock piece. You can do a quiet one like the Tanabe and at least won't be choking the system at the end.

Right... why would they put the slower, antique, transmission on the faster car?

See also the lack of a clutch pedal on the IS-F or LF-A.

 

Ok, thanks! I will look into the Tanabe exhaust.
Also true I forgot about the ISF, but its 8 speed auto at least shifts very fast.

 

The PPE headers on the 350 are claimed to provide a gain of 16rwhp. When I got mine I could notice some difference but not much sounds hella awesome though. This was the last piece I got after the f sport intake and exhaust and I coudln't tell much of a difference with both of them, maby a tad extra higher end torque with the intake but that was it. PPE gave it more of a oomph feel when I dropped them in as the last piece. 306 HP may not be alot but its still more then enough to get you in trouble =) Have fun

 

I can say that headers alone on a stock exhaust will not net and HP/TQ. At least that was my experience with Mazzuri headers. You will need to open up the rest of the exhaust somehow. My solution was Tanabe.

 

Correct me if I'm wrong, but I think with just aftermarket headers on a stock exhaust system you would be getting a bottleneck because of the stock piping's size, which would restrict airflow.

 

With stock headers the stock exhaust is a restriction. That's why you pick up hp just from an axle-back alone.

 

also a heads up. be prepared to get a check engine light.

 

No check engine light if the installer installed correctly , make sure to re-torque the section between the header flange meets the mid pipe. Also installed the 02 simulator correctly, make sure installer taking oem headers out and spray it with WD-40 and let it cool down before taking out those o2 sensors.That to prevented from stripping it , Dont use those screws that come with the after market header . Use OEM screws=it has locked end. After the install is done drive your car around at least 50 to 100 miles, comeback to the shop and recheck everything , lift up and re-torque it. Hope that help

 

Not with the O2 sim's installed correctly. (Although my CEL is on every other gas tank... "uh" I've never trouble shot it though to be honest)

 

Maybe your gas cap is defected ? warranty cover it, maybe there is a tsib on that ?

 

Oddly enough, it seems if i let the car idle for a loooong time it will go away, or if i drive very aggressively. The CEL doesnt really bother me though, i drove around for 18 months with the TPMS light on due to my old set of wheels not having them, i can handle a CEL.

 

Cool, this gives me some motivation to buy my headers. I was on the fence about it. Do the stock cats on an IS350 restrict airflow or do I also have to buy the high-flow cats they sell along with the PPE headers?

 

There's no reason to have high flow cats when u install after market header, its already illegal anyway lolz Most of the shop wont do any welder at the shop so you probably have to bring it to another shop and bring it back again. Too much hassle, there are stories that after install the after market high flow cats , those fell off.

 

Nice, definately putting in my order now. I'm guessing I should I also order one of those exhaust gaskets they sell?