Hi i have a 99 gs400 and just noticed a anoying exhaust leak and checked it out and it is coming from the left side y pipe below the cat and before where the two pipes come toghether before the first muffler or difusser whatever its called. My question is that pipe is really high from lexus but i found some replacement pipes but if gets rid of the two upper cats that mount to the manifolds and replaces them with a y section that bolts directly to the manifolds and has one convertor welded in at the end of the y pipes berfore the 1st diffuser. Was just wanting to know if anyone had had this problem before or tried this replacement pipe? Thanks in advance.

 

for one your car wont pass smog anymore, so unless you have a smog hook up to get you passed that when the times comes, that can be a royal PITA....if not you may find yourself without any choice but to buy the stock set up somewhere. I would find a used one from a totaled car or something, NEVER BUY PARTS FROM THE DEALER unless you are ok with paying 400% for everything they have.

OR

you can have the muffler shop cut and weld flanges to the Y-pipe you are thinking about buying so you can still use your stock cats then you will be in good shape and wont have to do what I said below. You will have to get those flanges from PPE Engineering though cause you wont be able to find them.

You will also have to buy o2 sensor "by-pass" spacer as well (picuted below) because if you dont your o2 sensors will throw a CEL code from the bad fumes which will basically "retard" the air/fuel and your car will run like crap or wont have any power.

Any chance of spot welding the leak if at all possible?