atoyot

what grey wire/tube is that in the first picture touching the header? Not worried about being burned or burning anything else with no heat sheilds?

jcrome04

Awesome dude.


Will sound amazing after proper X-pipe exhaust setup

Flat Four

No worries, its actually nowhere near the headers, just looks like it from that angle. I think the "ceramic" coating actually helped the underhood temp a bit.

Thanks Jcrome! I know... I cant wait for the dual set up. You should post up pics of your dual system from underneath the car.

jcrome04

Flat Four, here you go

JBrady

ACTUALLY, the headers were designed from the 98-00 GS manifolds.

I ***-umed that the stock manifolds were the same as I had taken pictures of the LS400 manifolds and purchased the GS400 manifolds that were used to prototype these headers... and they LOOKED IDENTICAL on first look... but the are NOT.

UNFORTUNATELY the 98-00 LS400 manifold is longer than the GS400 manifold and the catalyst 3-bolt flanges are rotated about 180 degrees. It would require very similar mods to the ones shown on this thread. Believe it or not I do NOT have them on my 99 LS400

That said the manifold pipe configuration is nearly identical with 3 decent stock primary tubes and 5 poor to VERY poor tubes. While not a perfect fit definitely a performance improvement. They are still on my list but other budget issues keep me distracted.

BTW, the stock Y pipe is actually a GOOD part with the exception of the nasty slash cut sections at the catalyst outlet.

Here are stock 1999 LS400 manifold pictures

Drivers side with the 2 "good" primaries on #1 and #3. The primaries on #5 and #7 are only about 1" long and intersect the other pipes at 90 degrees just like any junk log manifold. Actually for those cylinders a cast manifold of the same design would actually be better due to the way they are finished inside.

JBrady

Other view of the drivers stock manifold showing (barely) the #5 primary (what there is of it!)

Remember, the drivers side cylinders are the odd numbers, front to back (left to right as pictured below) 1,3,5,7

JBrady

Passenger side with the only good runner being #2 (first runner on the front)

#4 has about a 4 inch length hitting #2 runner at 90 degrees. This is the best of the BAD runners.

#6 and #7 both are 1" long, 90 degrees to a funky mini log.

JBrady

Here is the WORST runner of all. #7 actually feeds BACKWARDS into the #3 runner... UGHHH

JBrady

Here are the actual GS400 (2000 model) manifolds used to prototype the S&S headers. I post to show WHY I ***-umed the GS and LS manifolds were identical.

Drivers side

JBrady

1998-2000 GS400 passenger side exhaust manifold

JBrady

One more point.

I have not seen the 1995-1997 LS400 stock manifolds but I have seen the factory diagrams and they LOOK identical to the 1998-2000 LS400 manifolds EXCEPT...

The 95-97 have a small 2 bolt EGR flange on the passenger side. 98-00 do not have any EGR (done with VVTi)

PureDrifter

iTrader: (10)

good to know, thanks John.

Flat Four, did you have to remove the motor to put hte manifolds on? i was looking around in there and thinking it could be done without it...

steveski

What a sound - especially coming from such a clean 2nd gen I bet you really turn heads everywhere you go Nice job

JBrady

Ok, jcrome04, PLEASE do not be insulted by my following comments but I need to use your pictures to help show the forum the common mistakes that happen when a typical muffler shop does a "dual" exhaust system.

Starting with the catalyst outlets; the shop kept the first foot on each side. This keeps the funky slash cut section that I mentioned earlier and is the ONLY part of the stock Y pipe I would change. On earlier cars 90-94 there is no slash cut and I would simply KEEP the stock Y pipe as it is mandrel bent low grade stainless steel with a GOOD Y section. GS400s do not have the slash cust section only 95-00 LS400s.

From there the shop used either 2.25" or 2.5" (my guess from pics is 2.25" with is better) and then crush bent the pipe 2 times on each before the X pipe. The result is probably no more flow capacity than the stock mandrel bent 1.97" pipes. What is gained here? Nothing.

The X pipe is a Magnaflow part which is a universal formed part that has 2.00", 2.25" or 2.50" connections depending on which you order. The X itself is internally the same for all 3 part numbers and is decent for a 2.50" application, so-so for 2.25" and poor for 2.00" systems. It is too large internally and the outlet shape due to the sizing outlined above creates a compromised outlet flow. Even on the 2.50" use the design has the outlet pipes inserted into the X section which is the wrong way to build a performance exhaust as it creates sharp edges that cause turbulence restricting flow and reducing the entire reason for the X pipe.

I recommend the STOCK Y-pipe. Simply cut the pipe just AFTER the Y section and then either a section of 2.50" pipe (just like on Flat Four's... keep your Y pipe) or you can use a DECENT 2.50" to dual 2.25" or dual 2.00" outlet Y pipe to create a GOOD X pipe.

DO NOT get the Magnaflow Y pipe as it is worse than their X pipe



A MUCH BETTER design is one from Dr.GAS





EVEN BETTER... simply call S&S headers and order a 2-into-1 parallel merge collector with 2.00" or 2.25" inch into a 2.50". Should be under $50




Another concern is the "Cherry Bomb" glasspacks. These have louvers that are punched into the exhaust gas flow. They flow less than the typical turbo muffler due to internal turbulence. Get better ones at Magnaflow, Dynomax, Borla or similar than have a smooth internal tube with holes drilled internally.



That said I LIKE the internal design of the new Cherry Bomb Vortex (like to see flow testing) and their Turbo muffler.

And FINALLY my last quibble with the builder of the above pictured system is the swaging after the Cherry Bombs is in the wrong direction. The feed pipe should ALWAYS fit INSIDE the receiving pipe. The picture shows the opposite. This is minor especially this far down the system but again shows that many/most muffler shops build systems that are durable and fit but are not engineered from a performance standpoint.

BEST of LUCK to EVERBODY

Flat Four

Right on the money, Jbrady. Glad you got a picture of the "funky log".... some folks didn't believe me.

No motor removal. It was extremely tight, especially on the driver side with all the steering column crap. Its kinda funny though....I dunno if the stock manifolds are generally bigger or what, but now with the S&Ss and no heatsheilds, there's room to spare on both sides.

Thanks Steve. The "temporary" exhaust still bothers me just a bit (the car feels un-finished), but the sound sure is fun. 40mph down shift 'stabs' are scary driving in town. Very SLP Loudmouth-ish...which essentially, it is.