ahhh John, you're just overly-cautious.

 

Correction:

The GS430 and SC430 appear to have the exact same Y pipe. The LS430 is very similar with a slight difference where it joins the muffler section.

GS430 Y pipe section diagram:

 

GS430 muffler section diagram:

 

LS430 Y pipe section

 

LS430 muffler section

 

Thanks. Where are the other 02 senors for the 430? on the header?

 

Yes, same place as 1998-2000 400s. Here is the diagram showing the drivers side manifold. The passenger side is shown but the layout is not apparent. It is the same for both sides. 2 decent runners per side. Remember, this is a bigger engine. The manifold to catalyst location does look just like the earlier design. Who knows, we may get lucky.

 

jbrady I hope it fits the 430.

 

JBrady if you can get all that to work, and fit my 03 GS430 then please make means now once all the R&D has been done. Lets us on in the $$$ for the parts.

 

To summarize: at this point I do NOT know if the GS430 exhaust manifolds locate the header to catalyst 3 bolt flange in the same location (position, orientation, bolt pattern, spacing) as the 400 manifolds. IF and this is a HUGE "IF" we are very lucky... Lexus kept the location exactly the same and the catalysts outlet flanges as well. If all this were to occur we could interchange GS400 and GS430 exhaust systems. DO NOT COUNT ON THIS. It is possible.

HOPEFULLY, the 430 catalysts will bolt to the headers. If so, this only leaves the 3rd catalyst to replace. I am not certain the car even needs the 3rd cat to pass tailpipe emissions sniffer tests but it would be required by a visual inspection.

IF it is necessary to create a new Y pipe I would suggest a careful cut to remove the 3rd cat from the stock pipe and allow it to be welded to a higher flow Y pipe would make the most sense. This process could be reversed fairly easily if needed in the future.

NOW, lets talk a little about the GS400 Y pipe. I have scheduled with another CL member to do some testing with his 1998 GS400 Y pipe this comming weekend. I may decide to build a replacement Y pipe for GS400 owners. This pipe would be recommended with the headers (or another high flow Y) and it could actually be used by GS400 owners even it they did not install headers. Stock size is dual 50mm (1.97") OD pipes feeding a single 60mm (2.36") OD center pipe. The upgraded size would be dual 2.25" (57mm) pipes feeding a single 2.50" (64mm)center pipe (with possibly 2.75" and 3.00" options). At this point please do not expect or plan to purchase this pipe through me but it may become a viable option. I should know more after next weekend. IF the above info on the 430 cars holds true , if produced, this pipe could be used on the GS430s... again, a bunch of IFs...

Unfortunately the only thing we can count on with the 430s is that the header will bolt up to the engine and fit in the engine compartment. 400s can use there stock cats, Y pipe and mufflers although upgrading the Y pipe is recommended. A single 50mm pipe is not much to carry 160hp (320hp /2 = 160hp that each pipe carries)

 

Jbrady is there anything any members here can do to help with the GS430 situation?

 

Ship me a stock Y pipe to test fit to a GS400.

 

Sewell Lexus is in Texas how far are you from him? Being he is a sponsor here do you think he will loan one out for a little while? Would you be able to send it back to him in the same condition as you recieve it? I am sure the 430 guys on here will chip in to cover shipping. Let's get a list of 430 guys willing to chip in for the shipping costs. I will call Darell at Sewell and see if he can do this.
Come on 430 guys step up to the plate.
1. Fisher503
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You know i'm in, but when will this all take place is what i need to know or I will do other mods instead..................

 

Sewell is in Dallas, about 275 miles from Houston. By all means ask him but I would guess it is a special order part. Yes, I would return it unused. Just need to see if it lines up with the catalysts, bolt holes and contours. This comming weekend would be ideal as I plan to pull the Y pipe off a GS400 and could test fit at the same time.