The stock exhaust manifold isn't too bad; it border lines as a stock header. But everything past that to the rear mufflers is filled with kinked, eneven piping and restrictive mufflers and cats. My goal is to have everything from the manifold back re-done w/ propper tubing and straight thru mufflers. I don't need to worry about cats, so I'll replace them with a set of mufflers up there (remember to get SS packed muffs being that close to the block). If you have to pass a sniffer, get some GOOD hi-flow cats. But other than that, install an X pipe and keep the pipes seperate, so as to maintain a true dual exhaust.

Here's my pecking order:

Stock manifold -> twin front mufflers (or cats depending on need) -> X pipe -> Twin main mufflers - Twin rear resonators -> Twin final mufflers -> Stylish Tips

If the cost of headers comes down, I'd be glad to install them, but money is tight right now, and no one has a good set at an honest price ion the states.

To answer your question; I'd recommend you go with hi-flow cats, replace that God awful huge *** heavy primary (middle) muffler, and retain the stock resonators and rear mufflers. While the exhaust is off, check your final rear mufflers and make sure they aren't clogged- I've seen them get so clogged it was amazing the car would even run right.

That should be an economical way of opening up the exhaust. I prefer to use an "x" pipe to balance everything out and to replace everything so I know its really an open exhaust, but that drives the cost up. Everyone has their opinion, and I'm just **** about some things some time. But for your needs, that main muffler needs to go and clean up the piping around it. The cats aren't the free'st flowing either. But always replace what you take off. Removing something and just replacing it with a pipe leads to a very loud car. I'm hoping mine will be just as quiet as stock with a hint of a growl at WOT.

Keith

 

Keith that big thing in the middle is a catalytic convertor. From the motor you go manifold, precats, joiner into the main cat, then back before the rear wheels you got resonators, then at the end your 40 pound mufflers.
My setup consists of stock to the main cat, a race cat with a better inlet. then 2 1/4 out to the magnaflow resonators. and then out to the ricer bombs. It's too loud, though - I'm going to put in a pair of mufflers, or one dual in dual out in the tunnel there running back from the cat.

 

Are you sure that thing in the middle is a cat. I removed mine already and I think it was the most restrictive part of the system as I have a mandrel bent system from the front cats back now. I thought the thing in the center was a resonator.

Raj

 

that's the main catalytic convertor.

 

Yeah , it's a cat - I'm an idiot. I'm at work and only in my spare time can I make my posts. I was thinking off my head and just picturing the exhaust with out thinking. Just sort of figured the cats ....then a bunch of resonators and mufflers. Its a big CAT, but since I'm yanking mine I never really thought about it. Sorry for the incorrect info....either way, change the damn thing.

Sorry Max, you're right - Thanks for catching it. You really don't need that big *** Cat, just the two front one's if you get good ones. Any way.

Sorry again.

Keith

 

I wonder if it would pass emissions like that..

 

My friends Prowler has the same kinda exhaust - 2 fronts and a huge main cat. We ripped them all off and put in two primary hi-flow cats instead, butted them with two straight thru (glasspack) mufflers then two resonators in the back before the tips. He passed emissions with it, and its not loud at all. Only problem is that cheeseball 6-cylinder sounds like a friggin power boat with twin evenrudes.

 

Keith, i'm also weary of intake mods, after seeing Peter Scott's data and hearing about those guys with the losses. I have a pretty sensitive butt dyno, and as I started fabricating an intake on the side, I removed the intake snorkel and found that the car developed a bog in first gear, very irritating, couldn't believe it affected the car like that. Anyone with a similar experience? In the meantime, i'll put the snorkel back in. Adam, for Pete's sake, let me see the two timeslips, then we can start cutting nice times. I'll tell you a reliable technique to cut a .300-.400 light on a Sportsman tree, and you must must cool that car down before a run, get to the track and park it for awhile, and ice the intake, remove the spare, jack, trunk panels, mats, all your CD's and crap like that (and subs and amps if they're in there), and the rear seat if you really wanna make sure you hit that time, it only takes a minute. What plugs are you using, and what are they gapped to? I'm assuming the caps/rotors/plugs/wires/PCV/air filter/fuel filter/engine oil/trans fluid/diff lube/Dex-Cool/vacuum lines/sensors are all fresh/up to spec, Climate ctrl off, radio off, windows/moonroof closed completely (open window acts like parachute), OD off, ECT to pwr, and very important, find a driving position that will allow you to manipulate the accelerator and brake the way you want for your staging and launch. Your shoes even matter. Deep staging can help that RT. No burnout, drive around that waterbox on your radials, don't even make any smoke, just spin 'em one time around to clean 'em, experiment with pressures, a radial won't hook at all with too little pressure, the footprint goes all funny, drop a few lbs to try to get a teeny bit of wrinkle out of those short sidewalls, but that's all. Inflate the front tyres to max press, less rolling resistance. Remove the driver's headlamp if you want. Try uncorking the exhaust if you feel like it. If you're really motivated, disconnect the front sway bar, but totally not needed at this horsepower, only if you still can't hook, and at that point i'll just lend you my Hoosiers. The proper launch on a radial will not smoke, will not squeal. A dead hook will bog the car, you want the tyre to skip a tiny bit, it should make an eh eh eh sound when launching. You should be able to torque-brake the motor to 2000 rpm and launch smoothly on a radial at the track, don't stomp it on the launch, sidestep the brake (just put your foot to the side and let the pedal pop up) but come into the gas, smooth and pretty rapid, you should be at full throttle by ten feet out at the most. Keeping an eye on the barometer helps too, learn the basics of barometric pressure/humidity and altitude and their effect on mixture and the internal combustion engine. What is the altitude of your track? What was the temp and barometer readings on the day and time of your run? I need to know your mph, that's the true indicator of hp. Cutting good times is an entire approach, a combination of driver technique, tuning/preparation of the vehicle, and Mother Nature.

 

I am still leary about this whole intake thing... they should put a warning on there that says "Unlike almost every car in the world, our stock intake is specially engineered to make power while restricting airflow - don't replace it!"
I gotta pull the intake to put in my shiny new polished intake box, so I'll put the stock crap back in, and I'll also give a shot to the WR V2 filter hooked to the stock intake pipe and see how it does. I'd hate to think that after all the work we put into the thing it loses power.. but to be fair I've NEVER seen an intake lose power on a dyno unless something else is getting messed up (ECU related issues). Even the Acura RSX gets 10 whp with one of these airbox/pipe/foam filter setups.
Next thing up: finding out how the MAF plays a role in all this. Stay tuned people, answers are coming. I would like a final answer to this question.

 

Put my snorkel back in today, problem solved. The bog is gone, but i've definitely lost a bit up top. Amazing, such a difference from a little schnazola. I guess i'll just put in a K&N panel filter for now and wait for some dyno results. I must have the most sensitive butt dyno in the state. I fear the problem with replacing the intake pipe is that you'll lose that resonant chamber that Lexus spent so much time designing. I guess we'll see.

 

Adam,I hope you get your car straightened out man,have you been able to check the fault codes in the ecm?
I've looked straight down the middle of my center resonator,and there were absolutely no cat-like features;the perforated tube inside ran full length,but maybe my car's different from a CA market car(?).
Max,there are some units made by Borla that resemble this,but are 3" instead of 2-3/8",like the original one,maybe that'd quiet things down a bit.

 

You are right, but READ the dyno results. You gain on average 5-10 easy.....no question, but you do loose hp somewhere else; and does it balance out? From my experience, in the SC it does not balance. But I encourage others to try for themselves.

This concept is very true especially in the rotary world of porting. You gain huge HP gains, but it comes at a price. What good is porting an engine to optimize power at 9000 rpm if your intake stalls at 7000 rpm. Kinda see the picture.

Our intakes are matched for our manifolds (distance/diameter/flow rate/pulse cycles,etc. ). Changing one of those components will off balance everything. Yes, you gain hp, but you also loose some somewhere. Just be careful.

 

You are right, but READ the dyno results. You gain on average 5-10 easy.....no question, but you do loose hp somewhere else; and does it balance out? From my experience, in the SC it does not balance. But I encourage others to try for themselves.

This concept is very true especially in the rotary world of porting. You gain huge HP gains, but it comes at a price. What good is porting an engine to optimize power at 9000 rpm if your intake stalls at 7000 rpm. Kinda see the picture.

Our intakes are matched for our manifolds (distance/diameter/flow rate/pulse cycles,etc. ). Changing one of those components will off balance everything. Yes, you gain hp, but you also loose some somewhere. Just be careful.

 

No losses for those cars... of course there might just not be enough hardware there to matter, the stock intake isn't much. Something I noticed in reading an article in Sport Compact Car (I think it was) they had a Civic hatch they decked out with all Spoon parts. Anyone that's heard of Spoon knows they're like HKS or Apex'i, just not in the US. The intake on the car wasn't a cone filter- it was a stock intake box with a carbon fiber pipe joining intake box and throttle body. I think I need to talk to an engineer