Hi all. I have a 2014 Lexus is250 with Tanabe axleback. Are there any other upgrades I can do for relatively inexpensive without causing issues, sacrificing gas mileage, or throwing codes? Maybe a cat delete? What does everyone on here have?

 

if you want to avoid codes / CEL then dont touch cat.. cut the resonator off

 

ive never seen a single exit exhaust done on the 3is, that could be an option for a custom setup

 

Leave the resonators as they are important for optimal exhaust flow and tune the exhaust note to sound unique while filtering out unwanted V6 drone. You can replace them with high flow resonators If you wish.

Start by replacing the factory h/x pipe with a nice stainless steel x pipe .

 

thanks! Which midpipe would you recommend?

 

You dont need to spend big bucks on name brand, just talk to a reputable exhaust shop and have them fabricate some custom stuff for you. Start with the x pipe and then replace the resonators separately if you're still looking for better sound.

 

I'm running secondary cat and resonator delete with a custom midpipe and x-pipe. To me the resonators made the car sound too camry like. The car sounds great no droning and great purr not overly loud, still feels like a luxury car. Best best is to go to a reputable shop who have been doing exhausts for a while. They should be able to make the car sound almost exactly how you want just by accurately telling them your needs.

 

You should definitely try playing around with some high flow resonators to really find the perfect sound. Otherwise your setup is good. Nowadays I would leave the secondaries in place for emissions purposes, but back in the day I had a BMW 528i with a secondary cat delete + a magnsflow muffler and I really loved the sound. The secondary cats free up some engine sound.

maybe the stock resonators are too restrictive, but once you find some good high flows to put into there, like MBRP or Vibrant, you'll never look back to unresonated again.

 

Personally in my opinion the car sounds like a freaking Camry with the resonators. Huge turnoff to an otherwise great vehicle. I did come over from a F32 335xi so maybe that's why it l love the sound. As my setup sounds a little European-ish imho. I went with 3inch all the way and 4inch tips. Haven't had any kind of emissions issues with the dealers or any lights/codes come up. And in fact many trusted sources have assured me deleting the secondary cats alone on this vehicle shouldn't cause emissions issues if done correctly.
What's the biggest difference between having resonators/ not having other than sound? We only deleted the resonators after having the full system built and it STILL had that mechanical sounding whine.

 

Resonators "resonate" your exhaust flow. I'd suggest you look it up for a more detailed explanation, but resonance is basically this type of "backpressure" which is a highly crucial component when it comes to balancing overall exhaust flow with back pressure. Most resonators in my opinion make the engine sound better by filtering out unwanted frequencies, but even if I preferred the sound of an unresonated exhaust I would never go unresonated because you are losing some performance.

for me, the way the exhaust flows and ensuring optimal resonance/back pressure is far more important than simply the "sound".

 

Most of the time resonators delete means custom especially when going full Custom.

 

Ah yeah good point. Back pressure is an important thing to keep in mind, especially for an NA engine. Geeked out on a bunch of videos explaining that a while back.

When I was a kid I had basically a muffler delete (resonators in place of mufflers). Chaned after a while because it was entirely obnoxious. And when I put my chamber mufflers on the car it actually was noticeably faster and quicker throttle response. That was also an NA 6cly.

 

Back pressure is a massive myth lmao. You need to do some more research. Slight (very slight) flow restriction can be good but you do NOT need back pressure on 99% of vehicles.

 

edited my post as you replied. This was my experience with my old 2JZ I6 cly....

When I was a kid I had basically a muffler delete (resonators in place of mufflers). Changed after a while because it was entirely obnoxious. And when I put my chamber mufflers on the car it actually was noticeably faster and quicker throttle response. That was also an NA 6cly.

 

I guess my explanation was a little too basic. By backpressure I mean exhaust gas resonance (basically causes turbulence, assists with exhaust flow).

Different from the sort of "back pressure" causes by a muffler. A restrictive muffler is good for the engine at 3000rpm and lower.