Well since the stainless steel exhaust tips seem to be falling off my '91 Q45 I've decided to get a whole new performance muffler. Now I know the Q45's rear muffler is about as free-flow as it can get, but I want to lose the added weight that those mufflers obtain and get a nice low growl. I've thought about Borla, Greddy, HKS and a couple of others, but I wanna know what you guys think or have had experiance with. Any help or opinions would be greatly appreciated. Thanks!!!

Freddy B has a really nice throaty growl on his Q. Not sure how much of that is exhaust and how much is cone intake, but I was impressed. A bit loud, and very aggressive. I *think* he has a Borla, but I can't remember for sure. Not sure how often he checks in, so email him for his thoughts.

i removed that third muffler and replaced the other two with borlas, and i also have the exhaust exiting at both corners now. it sounds good, although there is some interior resonance.

I believe Fred has removed the stock rear muffler and replaced with ANSA resonator tips. The install looks clean and I think he said it dropped about 60 pounds from the rear of the car...

Well...in thinkin it over I'm gonna get rid of all 3 mufflers and just do 2 Supertrapp mufflers. Tune the discs correctly so i get a little bit more backpressure to raise my torqe a little. I'll get pics up when its done. Thanks folks!!!

Why do you think that a car with 2 cats on each exhaust manifold needs back pressure to raise the torque.

This was old school when Chevys used big overlapped cams. Don't disturb the cross over pipe location as this is tuned for 4,000 rpm.

Severe resonances inside cabin will occur if you don't have premuffs [resonators] and wait till the tail pipes to do anything sound wise.We have built systems where the stockstraight thru premuffs were left as is and nothing but pipes to the rear. This provides the most noise and power gain [something close to 10 HP with a JWT ecu] less with stock ecu!Maybe some 6" diameter rear flairs and a propane flame ejector!

Q45tech wrote:Maybe some 6" diameter rear flairs and a propane flame ejector!

I dunno if this was sarcasm or putting me down, but I don't appreciate it. I'm not ricing out my Q45 (like some Fast and the Furious punk), I am mearly trying to kill 2 birds with 1 stone. I'm wanting to lose the weight caused by the rear muffler and add the possibility of tuning my exhaust at a moments notice. The Supertrapp mufflers would also add a different look for my car. If you don't like the idea then fine, but you don't have to make fun of the idea.

Q45tech wrote:We have built systems where the stockstraight thru premuffs were left as is and nothing but pipes to the rear. This provides the most noise and power gain [something close to 10 HP with a JWT ecu] less with stock ecu!

Dennis, I'm new at this car tuning stuff. Would you please explain what you mean by nothing but pipes to the rear?

I wasn't putting you or your idea down! Just pointing out that there are serious problems in choking off the very end of the exhaust process as the waves bounce back and forth between the restrictions [last cat] and end of pipe. These waves can lead to big time cancellations of power

Actually you need an [impedance] matching device [taperd trumpet] to slowly spead the confined wave out to match the air as an abrupt shift is what starts the reflections.If you look on the Q exhaust you will see welded on rubber vibration dampeners!Till you have tried getting a decent sound without multiple floor pan seat vibrations making your body numb you may think any old thing will do.

I love the idea of flames shooting out, sure way to make a tail gateing driver back off! Hank Hill loves Propane and so do I.

Ever hear of my idea for a high power automotive laser to burn holes in tires [be prepared to accelerate briskly] as the SUV in your rear starts to flip....all it takes is another BIG alternator to charge the capacitors less than $10,000 worth of components to protect you from tailgaters ----- takes about 3-5 minutes to charge up for the next shot....and the beam is invisible! Use the rear camera as a tracking sight.

The above is a joke but quite technically feasable! Dump a few 100 flacets [from under the rear] but that would be indiscriminate unless you own a towing service and have kids to put thru college and they might have witnesses who see them coming.

I have a technical warped side that is world class!

NOTHING BUT PIPES TO REAR:Our muffler shop [which makes really exotic systems for SLP Engineering Z28/Corvettes, etc] has a cheapo package where they remove the entire exhaust system from the premufs back and replace with just straight pipes [a few bends].......sounds loud and funny like an old V8 with a hole in the muffler! But some like the sound....severe resonances 55-80 mph!

By the way we put an aero/skirt kit on a ragged out Q with this exhaust system plus red neon all around the under with a $4,000 runny Cherry Red paint job, our Cambodian tech sold the car [his personal vehicle] for $12,000 cash and threw in a rice cooker [that I gave him for Xmas]......honest truth!

Q45tech wrote:NOTHING BUT PIPES TO REAR:Our muffler shop [which makes really exotic systems for SLP Engineering Z28/Corvettes, etc] has a cheapo package where they remove the entire exhaust system from the premufs back and replace with just straight pipes

What's the name of the shop? Might as well talk to them. I might consider replacing the rear muffler with something more fun (Flowmaster?).

Anything under $300 gets my attention. :thinker

Who said it was under $300? Grand Muffler can make you anything you want.

I was wrong Sonny's Red Q had pipes from the rear cats no mufflers what so ever...............loud in the extreme sense of the word! ----------- No faster but loud. Required a bullhorn to communicate with the passenger.

Q45tech wrote:Who said it was under $300? Grand Muffler can make you anything you want.

I was wrong Sonny's Red Q had pipes from the rear cats no mufflers what so ever...............loud in the extreme sense of the word! ----------- No faster but loud. Required a bullhorn to communicate with the passenger.

And I was just about to ask if "Our Muffler Shop" was Grand Muffler

Oh by the way Dennis, the other day my mom and her boss took her boss's car to you guys to get a tune up. It's a Lexus of some kind. Anyway, my mom comes home and says "have you ever heard of T3? This place is awesome, you should check it out." And I tell her, "yeah, one of the Nico moderators works there." Then she says "gosh, you know somebody everywhere."

Anyway, just a interesting story

Has anyone thought about getting custom built systems from aTRUE performance shop?

The place that did AGM's in Perth Australia, got some incredible results from designing & manufacturing their own Headers, Mufflers & Mandrel bent system.

They tested the power on the dyno before & after, & every mod they made, they tested it again to make sure they were going forward.

I spoke to the guys for 35 minutes & this guy knew what he was on about.

You will probably need to find a shop the Racers use, as others will say they know & just charge big bucks for noise.

Hey Chally, are you talking about Jeff Garland at Exhaust Dynamics?

AGM had said that there were substantial gains with the system that Exhaust Dynamics made for him.

Their website: http://www.exhaustdynamics.com.au/about.html

Based on my experiences, I would suggest replacing the rear muffler only, either with a free-flow unit or if you want to save some weight and increase noise, replace it with resonator-tips.

I tried out a bunch of different stuff. First, I replaced the rear muffler w/ a MagnaFlow. That was good. Then, I thought, "What if I replaced the mufflers after the cats with a straight pipe?" That was not so good. Too loud, sounded like a pickup truck with dual exhausts. The resonance was unbearable.

I replaced the straight pipes w/ MagnaFlows as well and the tone and sound level is very pleasing.

The first set of mufflers are of a straight-through design and, in my opinion, they do not need to be replaced.

The Q has a very efficient exhaust system and it is hard to pickup substantial horsepower without re-doing the whole setup.

-sijoko

Hep, That's the guy.They gained about 45hp on a stock engine & DIDN'T lose low down torque . Maybe AGM will fill you in with what he wants us to know.

The biggest problem with the US Q's is that you have a Pre Cat in the headers, where as we just have pipe, & when you see how small the outlet is from each side, you instantly know it's going to be a restriction.

I had a Datsun 1600 that had bigger engine pipes than the Q, & for maximum HP, you needed 1 1/2" header pipes dumping into a 2 1/2" pipe. When you qheck the Q's, it dumps into about a 2 1/4" pipe (& mayb smaller) for a bigger amount of gas. (1/2 of 4.5L= 2.25L, so just in theory, it should be bigger than what's best for the 1600 engine.)

That's why I suggested a bloke that makes exhausts for the racers, as they should know how to keep them quiet as well.

There's a guy in our suburb that makes his own mufflers, you can see straight through them, but the noise is very reasonable & in no way annoying. In fact, I has a supposed quiet sports system fitted by Midas, (to my last car) & the noise was SO loud, we had to wind up the windows, it was embarrasing, & they used so called quiet mufflers???, but when this other guy put his on, it was beautiful & it went better.

The engines we get from Japan don't have the precats welded to the stainless steel headers. We must swap headers [use the ones on the bad engine] on the newer engine to comply with US emission regs.That said we have one Q that was tested on the dyno with the Japanese headers prior to changing them to comply."I have heard but cannot publically comment that there might be a few Q in US with non compliant [no precat] headers installed in states/areas without emission testing.........they will fail a cold start test and may not pass the HC portion depending on miles on the main cat"

The best we found was 5-6 HP difference as the precats interior honeycomb is quite open with good see through air space. Very loud straight thru mufflers can bring this up another 6-8 HP so one could get another 15 HP total on top of the 25 HP one gains with a JWT ecu........in combo 40 HP Remember when you change exhaust headers the cams have been optimized to work with the slight back pressure of the precats so little is gained and much can be lost especially in low to mid rpm smothness.

The 90-93 Q engine was optimized to create as much torque as possible in the 3300-4500 rpm range and 337 lb/ft is easy to accomplish [4-5 more than the newest engine since they gave up peak torque for higher HP in the 6,000-6,400 range to get the numbers for cache].

The torque on the new engine is 280-283 lb/ft at 6,300 vs 269 @ 6000 [258 @ 6300] or so on the 90-93.

These fellas on WA (Western Australia) did a lot of research on the correct metals to use for the headers & did a lot of Maths to work out what was best for this particular engine. They even got the design specs from Japan, so they weren't just guessing. They also Coated the headers, which elimanated the need for heat shields, & allowed for a larger pipe as well.

If you wanted to chat to him, I'm sure he'd be only too happy, but as for the secrets they may have uncovered, I think they will stay with him...

I've written down the figures he got, but I 've temporarily lost them. (I hope )