Celtica

I've been trying to read up on various threads on these forums about exhaust mods and I came across this link; https://www.clublexus.com/forums/per...st-w-pics.html
I would like to try the same set up, just get true dual piping after the cats and leave the resonators & stock mufflers in place. Since this guy has a "98 with VVTI like mine, I'm thinking I'll get hopefully 10-15 hp without loss in torque ? Anyway, could someone please explain what an X or H pipe is for and how does it help performance ? Thanks in advance !

Celtica

Anyone ???

1JZPWRD

iTrader: (59)

I was under the impression that the X pipe will equal out the exhaust gases more quicker, which entails better performance. This is what I had, and it also seems that a 10 inch long X pipe is the best for our setups with either V8's. Again this is what I understand from the research that I have read on here. I personally had the 10 inch long X pipe installed with stock mufflers, no cats, and aftermarket resonators. When I removed the resonators, I actually lost power, i could tell alot from the gas pedal.

TheAzn

iTrader: (2)

H and X pipes are to equalize exhaust pressures. Depending on engine performance, the H or the X pipe would improve performance. X pipe has a better flowrate.

Celtica

Thanks, guys.. It sounds like I should do the x pipe to maybe 2.25" piping after the cats and leave the rest alone as I don't want to lose any torque..

snakehead

iTrader: (1)

I am getting close to installing Rush headers, new exhaust, x pipe,
Worried about how loud this might be, does any one know how to quite things down , type of mufflers , resonators , etc...I will be running test pipe instead of cats or should I just gut out the stock cats and relocate them ?

I understand its going to be loud regardless with the Rush headers but if there is a design that helps lessen the DB levels please let me know..

Thank you,

Ali SC3

iTrader: (10)

resonators, one in each pipe before the muffler is the way to quiet down a true dual exhaust system with headers (Aside from or in addition to a large center resonator). It wont even quiet down at first you will have to run it till the inside gets coated till things will quiet down.

the X pipe equalizes the pulses from each bank and that keeps the overall velocity of the exhaust gasses up. You don't want too much scavenging, but the X pipe is generally beneficial.

2jznosht

H pipe is better at lower rpms's where as an x pipe shines at higher rpm's. if the 400's are like the 300's then an x would be best due to power being made higher in the rpm range.

Celtica

This has me wondering, will there be any loss of low end by switching to the afore mentioned dual exhaust set up ?

scENFORCER

You will lose low end power. If you have the vvt-i model I strongly suggest you consider a Y pipe, especially if you'll be installing headers. Lemme find some links for you..

scENFORCER

Here you go..
Its a bit of reading, but I strongly suggest you follow some of the links within the links I posted. Lots of useful information on vvt-i 1UZ's exhaust routes.

https://www.clublexus.com/forums/per...-98-sc430.html

https://www.clublexus.com/forums/per...m-exhaust.html

..I recently purchased "bcsc400's" 99 SC, and I can tell you the thing is a BEAST with simple BFI, LSD and full custom exhaust that was properly researched and done. Feels 10x faster than my stock '99.

Celtica

Thanks SCenforcer ! I will be reading for sure ! I wish I could get a pic of my car on my signature, but I can't even find the option. My car looks identical to yours !

Celtica

Plus, I'm going to need to read up more on this BFI mod I keep hearing about..

scENFORCER

98+ SC400's have 2 options for this..

1) SRT Intake (~$500). Nice looking intake with a piggy-pack style ecu (chip) that leans out your AFR a bit.
2) eBay BFI (~$130). Home-made style BFI which works very well. The guy started mass producing the kits and selling them on eBay. This is what I have installed on my car and sounds/works great!

..both claim to give you about 15-20 wheel hp, but I dont think anyones actually done a dyno with just this installed to compare. I personally think it works best with supporing mods like an exhuast.

Celtica

Wow, hey thanks, you've given me all kinds of helpful info today. My plans are to try to squeeze an exrta 10 or so hp to get to the 300 mark, get a strut tower brace and call it a day as I'm already very happy with the looks and performance of this car..