bluebird71

iTrader: (54)

I am putting parts together to swap an LS6/T56 into my Lexus IS300. I want the car to be as low key and sleeper as possible so I can really surprise the hell out of a few guys around here. It will have to have custom fabbed LT headers to fit so that will make it a lot louder right there, a mild cam, which again makes it that much louder, and I wasn't planning on putting any cats on either. I was relying on this setup to suit my needs and provide plenty of power:
-3" pipes off headers merging into high velocity collector which turns into a 4"
-4" electric cutout
-Then stepped down into the stock Lexus 2.25" catback

My last T/A did GREAT with this 4" merge Y/cutout combo, even on a nearly stock catback. I figure the stock Lexus catback will do a lot to keep it quiet, even with longtubes, a cam, and no cats. I'm just wondering, even with the big 4" cutout open, will the exhaust slamming down into the restrictive 2.25" hurt the performance significantly?

01ssreda4

iTrader: (96)

Thats gonna depend on the individual muffler. Remember that muffler was likely not designed to handle near that big of an engine.

bluebird71

iTrader: (54)

Yeah, thats why I figured it would be so quiet though. On the other hand, it wouldn't be too good if it trapped too much heat and gasses when the cutout was closed, which would be the majority of the time. I'll just go with a stock f-body muffler or something like an SLP Dual/Dual (which is what I had before) if its totally necessary. Even that was louder than what I really want with this though, even with the cutout closed and a 224/230 cam.

01ssreda4

iTrader: (96)

A dual/dual flows better then a stock f body muffler. The stock muffler should be dead silent though, at the expense of hp, obviously. Dual, Dual will give you a hint of sound but give you some hp back when the cut-out is closed. Tough decision.

BOBS99SS

iTrader: (2)

That's gonna be a sweet build ,my buddy did a is300 but with some jzitzu motor and a turbo,was a fun car though, a ls motor is gonna be pretty sweet,I don't know about the stock muffler,I see that beeing one hell of a restriction,I saw on 2 guys garage where they did a m5 with a ls3,they custom made a dual exhaust with a lot of magnaflow stuff,he didn't want it loud at all,but didn't want a restriction

bluebird71

iTrader: (54)

Dedicated-Matt was the first to do the LS1 swap in an IS300 with this car:





He made this first Y setup mostly out of aluminum so it was super light:



This first Y had only 2.5" pipes going into a 3" merge. Mine would be 2 3" pipes going into a 4".



This year he upgraded to an LS3:



He also went from the Y setup to a custom true dual:







This guy does some amazing work. He actually has this car up for sale right now for $25k, which is hard to immulate considering all the parts, fab work, and labor involved, not to mention other upgrades he has done like a $3k coilover kit. I was already in the process of putting together parts to convert my black '02 IS so I guess I'll just keep chippin away at it little by little myself. I have a great 35k mile LS6 out of an '04 Z06 to work with so I think it will turn out pretty nice.

JRENIGAR

iTrader: (37)

damn, now thats a nice car and setup. I love the exhaust work. Hell, Id trade my ls1 car for that, not that mines worth it though....

TImmy_Jones

iTrader: (4)

Hooker aerochamber muffler.

bluebird71

iTrader: (54)

So which is quieter, the SLP Dual/Dual or the Hooker Aerochamber?

99Bluz28

iTrader: (35)

IMO, it looks like you could run a Magnaflow #12599(dual 3" in/out) in place of the merger then run 3" mandrel bends out of it into a Magnaflow #11219 (3" in/out) on the left and right side. You wouldn't lose any flow so you could totally skip on using a cut-out, and considering your setup it should be fairly quiet. If you want it even quieter then run a Magnaflow # 12909 (3.5" in/out) right after the merger then run it into a single Magnaflow #14151 (3.5" in/out) or into 2 Magnaflow #11219's(3" in/out) one on each side, which should be quieter yet.

bluebird71

iTrader: (54)

Yeah, that's an idea, although I did LOVE the effect of being able to open the cutout and go from Bruce Banner to Hulk instantly. With the high velocity merge and the big 4" cutout, it actually picked up better dyno numbers than a true dual setup due to the sweet scavenging effect. I could always do the big Y setup with dual mufflers and tips though. As you can see, there is a LOT more room to work with under there than with an f-body.

WSsick

iTrader: (13)

I'd try and get a bullet muffler or two in there if you can (Y/X will decide how many) to quiet it down that little bit more. My friend had a dumped Spiral Flow and it was considerably quieter than my dynomax bullets...but mine was an X oppposed to his Y.

MeentSS02

iTrader: (11)

The SLP Dual/Dual - at idle and cruising, they are pretty similar, but at WOT, the Hooker was considerably louder.