ATSOU

Wow......so complicate..........will that add some HP?

Richie

That looks very good !!

retrodrive

Those 2 bends at the rear part of the exhausts look kind-of sharp. Is there no way to straighten the whole thing a little bit more or there is no need to?

LOTC

Looks like the plan is finally coming together John. Let us know how it goes.

JBrady

retro, while the bends look sharp they are actually not a problem. Compared to the stock system this one is WAY better flowing. Afterall, I do not expect there is more than 25hp to be gained at best so if this configuation costs 5 of those 25hp... I am still 20hp ahead

Actually, the design was dictated by the area available for mid-car silencer/mufflers. I want to run mufflers here as this will (hopefully) allow me to keep the stock final mufflers for near silent normal operation and a quick 10 minutes later, drop off those to run a VERY low restriction system that can still be driven by a cop car without getting pulled over

This system is actually built so that I can run various configurations and test both sound level, quality and performance. Once I determine the best overall system I hope to offer duplications to those interested. With minor mods this should be adaptible to ALL year and model Lexus V8 cars including LS, GS and SCs.

Japanimal

Will the exhaust you have planned be any lighter than the stock setup??

persian451

that setup shows you only have 2 cats... however on the 91s i know have the third cat where you x pipe is located...

JBrady

Since I am keeping the same basic configuration as stock only with MUCH better flowing components and scavenging potential... the weight should not change more than 5 pounds one way or the other. However, with the drop off muffler ease of my muffler delete mod, something that will still be very easy to do with this design... a near instant saving of 20-30 pounds is 10 minutes away. In other words, you can run this system with 2 or 4 mufflers quickly and easily depending on your mood for the day

I will also build some straight pipes from the center mufflers (previously the silencer position) and try them in different sizes including 2.00", 2.25" and 2.50" to see if there is a performance change.

JBrady

The 1st gen LS400s and SC400s that were California certified had 3 catalysts with the first 2 attached to the exhaust manifolds and the 3rd in the middle after the Y junction. The other 49 state cars had just the 2. If you modify a California car IN California technically it will not be 100% legal BUT many non-California cars are taken into the state and are legal with just the 2 cats because of this. So, the technicians doing smog testing will probably never notice if you have the 2 cats and it should pass the sniffer test NO PROBLEM with just the 2 cats. Now the California cars do have a sticker on them and if you check the VIN number you can find out how the car was originally equipped BUT if it were me I would just loose that 3rd cat and build this same type of system. I am certain you can get it smogged somewhere with no hassle at all. But, this is only my opinion and I don't live in California.

lspower

how much would i gain if i just replaced the 2 back mufflers w/ straight through mufflers and had the resanator taken out and replaced w/ straight pipe? (i already took off 2 muffs)

Lvangundy

Nobody here has done any official dyno testing with each part of the exhaust removed separately.

You can only speculate and estimate how much of a gain you will get. Otherwise it's time for testing with some kind of metering device like a G-tech or a dyno run.

JBrady

Lee is correct in saying that no official testing is posted on this site anyway.

I would suggest that between 7-15hp and similar torque is available if you do the merges correctly. If you do them incorrectly you can actually loose power.

For a first gen 250hp (rated, 230hp more realistic) 1UZ-FE... I would suggest going with a high flow 2" into 2.5" Y-pipe with about 2 feet of 2.5" center piping (either straight pipe or straight through resonator like a Magnaflow or Ultraflow) and then Y it back into duals. You could go with 2.25" like me and in fact an SC400 owner claims to have accross the board gains with dual 2.5" pipes but I would suggest that you will almost certainly give up low RPM torque and make the car feel slower around town.

If you want me to build you some pipes PM me.

SilverFlare

since u know we hv the same model of LS, plus i hv the rear muffler already... I m not kidding pls build one for me!!!

lspower

i decided on getting a 2.5 dual catback with ghl motorsports mufflers ? i cant wait to hear what it sounds like.. anyone have 2 cents on it?

thanks
ryan

persian451

how much do you think the piping alone costs? must I change the mufflers when doing this to the 1st gen