AmbyBomb

Does anyone have pictures of the stock exhaust routing? I'm interested to see if there are any pinch points near the muffler. I had thought that there was, like the RCF, but I'm not so sure seeing the aftermarket offerings.

tapjoy

Theres a good view of underneath the car in this video. Maybe you’ll see what you’re looking for.

AmbyBomb

So it looks like the exhaust is actually flattened as it passes under the diff.

IssaV8

Stock vs GTHaus


The factory piping is indeed "smooshed" for the axleback portion. Edit to add: There are no fitment issues with the "unflattened" aftermarket portions.

wthrman2

Wow, these pics truly show the "flattened part" so well. Wonder why Lexus did this if it wasn't essential but I am sure they had their reasons

tapjoy

probably for noise or something? It’s odd, I haven’t seen or heard of that in other cars but maybe it’s more common?

Answer

I'm pretty sure the axelback is the same one found on the RCF and GSF, so maybe one of these had a clearance issue under the rear crossmember and they had to crush it a lil bit. Mostly, they didn't engineered a new axleback for the 500 and used parts that already existed.

Renault

I would imagine so since there would be a restriction of airflow. Can anyone confirm this makes it quieter?

AmbyBomb

I suspect it's more for clearance than noise.

IssaV8

Seeing that the aftermarket portion is not flattened and needs no modifications to fit, I think it’s safe to say it’s not for clearance issues. Could be for sound or higher back pressure, or something else entirely.

AmbyBomb

Or the aftermarket isn't concerned about an extra half inch or so of clearance.

IssaV8

Given the squish is at the top towards the vehicle, and I have no parts touching even with the aftermarket- I still think it’s for other reasons.

MYIS500

With the exception of smooth looks, I am curious to know how the stock system would sound if the secondary cats and resonators are removed to match the GT Haus system. The sound could be worse, better, or similar. But...first I have to get the car. May look into this next spring.

AmbyBomb

There are clips in another thread for that.

BitterJoke

There are clips of my car with a Gthaus cat-back in the other exhaust threads