matrixgts

iTrader: (1)

this maybe a stupid question.is the xpipe causing the drone/rasp or would a ypipe set up or any other set up get the same rasp/drone.

matrixgts

iTrader: (1)

it looks like he used just 1 resonator.

jgscott

iTrader: (1)

I did a lot of research on the later year VVTI SC exhaust system mods. J Brady is right about the X sections. The Factory one's were real good, and another thing about them I learned after 3 SC400's is that they have a Center divider plate in the middle, and that they are flared to make a Venturi effect which sucks the exhaust out of the Exhaush ports.

Also the Center Muffler you have may be a little to large, as I made the same mistake, you want the hot gas to exit/ get in and out, asap without swirling and delaying in a large canister.

I'll tell everone a quick trick I learned, that's cheap and works.

Leave the stock exhaust and Modify this way:

1. Remove the Center Cat or Res which ever year you have and replace it with 2 1/4 or 2 1/2 Straight pipe.

2. Look at the flat crimped pipe on the stock system which is down to 1 3/4 inch and 2 inch. Cut it and add 2 1/4 Mandel bends. ( Look Near Rear drive )

3. Add Headers, no matter which ones. The IMF or a good option middle of the road of the shorty's or the Long tube Aussie headers.

4. Do a BFI. The other intakes Suck IMO.

5. Theres another Trick thats Cheap with the CAT's but you'll need 2 O2 Sims.

Heres the custom system I built and SOLD Below.

https://www.clublexus.com/forums/per...nomax-pic.html

https://www.clublexus.com/forums/sc4...drel-bent.html

JBrady

You definitely want a good craftsman to build your system. I like you plan but not sure if the Burns mufflers are right for the project. For much less you could go Magnaflow or similar. I would re-use the stock cats they are great so no need to spend more there either. I would change the IMF collectors for Burns type 4-1 or even three 2-1 per side for a tri-y design. The smaller the collector volume the better. If you are buying from Burns have them run their calculator for you in terms of pipe size and location of cross overs. Let us know what they say. Finish the project off with a good dyno tune.

bcsc400

iTrader: (1)

If I went with the IMF headers and made the changes to the y pipe with the stock cats under the car, how would you design the merge into the resonator?

Da Coupe

iTrader: (7)

I'll definitely post up full specs and dyno #'s once completed

JBrady

Your question is actually more complicated than it seems.

I am often asked what I recommend and my normal response is the STOCK part. As jgscott confirms that section works very well. It looks restrictive but has supported 400rwhp.

That being said there is definitely room for improvement but I have never seen anyone do it correctly. I actually donated a 2.25" - 2.50" Burns "style" merge to a member who had a 2.25 into 2.50 made out of it. Low end was definitely lost. One of the reasons your system works as well as it does is it keeps most of the factory 50mm (1.97") primary pipes.

I am actually in the process of designing a Y pipe for my 1999 LS400 (same engine and transmission as SC400). I have a merge design that works very similar to the excellent factory scavenging Y section but with more peak flow capability. Obviously, I would recommend my design. Of course it is not available yet. PM me if you would like more details.

Regarding the stock cats that is also tricky. Being round I am not certain of the ground clearance. My above recommendation is theoretical as the stock parts are excellent flowing cats. The large 3 bolt flange is another concern. All in all it may make sense to go with aftermarket round METAL substrate cats IF you go with the IMF headers.

Now, performance wise I have heard very little on the IMF parts other than "good" and they "work" which I am sure is true. I would also suggest most are not using a catalyst with them or possibly a single center catalyst. On our engines with VERY conservative cam profiles their is very little to be gained with long tubes over short tubes. Not one of the available headers are actual tuned designs. Not the S&S, not the IMF and not the Aussy ones. So, for me it is a choice to get the best performance with the best fitment and functionality.

From the perspective of using catalysts it is hard to beat the functionality of the S&S headers. They allow you to keep the stock excellent cats in the stock position. On the SC they will lower the outlets slightly and not match up with the stock Y pipe. The mods needed from there are minimal and the result would be the least compromised ground clearance compared to any under car dual catalyst choice.

Here is a link with 2 members using the S&S on 1998-2000 SC400s one with and one without cats.
https://www.clublexus.com/forums/per...s-install.html
Member SRQ400 also has pictures of the undercar install here:
http://mysite.verizon.net/res6pb6m/id11.html

While I like the stainless construction of the IMF parts and they are "pretty" they are not "tuned", the pipe size is larger than i would recommend and the collector volume larger than I recommend. The S&S with ceramic coating will likely outlast your ownership and provide and excellent power increase. On a supercharged GS430 with a STOCK Y pipe they gained as much as 40rwhp. Everything is a compromise. If it were me I would use the S&S with minor mods to your current exhaust design to get the best overall performance.

bcsc400

iTrader: (1)

Thanks, the S&S headers make the most sense.
I wanted to use the stock cats and hopefully not have to deal with a CEL.
Even with the stock suspension ride height, I wouldn't want to risk damage to the exhaust.

Beebo

where did you order the Tanabe Medalion Touring exhaust? is it just the mufflers and tips or an axle back right after the y-pipe?

my friend wants to do a similar exhaust on his SC400. im sure we can save a bit of money making our own y-pipes instead of buying the Magnaflow y-pipe's

any help is greatly appreciated

-Wes

t70 supra

iTrader: (-4)

threads 1yr old pm him noob

Beebo

Noooooooob? not even... im just trying to help out, he's the one with the SC400 but your right ill PM the OP

bcsc400

iTrader: (1)

The Tanabe is an axle back. I purchased it from an eBay seller but there are good vendors here you can purchase it from. I get many compliments about the sound of the exhaust.

stockhatch

iTrader: (12)

Car sounds righteous man.

kwg

iTrader: (1)

Looks amazing!

Beebo

Thank you sir