GT Premi,

That's a good one, you claim that you can tell by the sound of a clip found on the internet whether or not the exaust system has enough back pressure to produce torque down low or up high. Maybe they could hire you and save all that dyno time they claim to be burning to develop their exaust systems. I think we'd be very lucky if the clips sounded even just close to what the exaust systems installed on a car sounded like in the real world. These are just clips with no control over what and how they were produced, you have to hear them in person to know what the car and exaust system really sounds like. The clips can only give you an overall idea of the sound.

Personally I like the sound of Flowmaster Delta50's on a small block with long tube headers and an X-pipe but this is not at all what the new Flowmaster '05 GT system sounds like. I like the sound headers on a V-8 make at idle and I like a slight bite to the exaust, closer to the open exaust I'm used to hearing at Vintage Trans-Am races and the strip. I'm a professional motorsports photographer I know and love the shriek of F1 engines, the subdued scream and whoose of Champ Cars, the thunder and bark of Trans-Am cars and the positively explosive report of an NHRA Fuel class car launching at the start. I hate the drone of NASCAR series cars and truck and the flat bumble bee sound of most of the small 4 and 6 hole spec class roadracers.

 

Flowmaster is old 80s technology. Corsa is the way to go.. porven HP.. wheres flowmasters dyno chart?? -WORD [sm=bustedsign.gif]

 

I like Flowmasters too , I had them on my restored 1966 2+2. They were great, I had some 2 chambers with turn downs initally but this was too loud inside for long distance driving so I had my local custom shop bend some pipes over the axle and out the rear valance of the car GT style.

This is what I said before seeing your post, these clips are hard to really get a feel for the system and you cannot be sure what you are hearing. BTW the clip I posted for the '05 JBA system is on a blown '05 GT automatic with JBA long tube headders, JBA off-road (no cats), H-pipe and the new JBA '05 GT mufflers at the rear. The sound on an 05 GT with JBA shortys and JBA H-pipe with cats and JBA rear mufflers is not much different but with less bite and rattle at idle.

 

I actually like that Corsa one.

Happy now?

[edit]
Whoa! Just looked at the price. I don't like it that much! $695

 

I don't like exhausts with baffels/louvers inside (Flowmaster), but I'm more interested in performance than sound. The Loudmouths seem like the best of both. I don't see how any muffler can outperform a straight open pipe. There are tuned mufflers that are also "flow through" or open pipe design, but they cause air turbulance to make their signature sound.

 

Hi GT Premi,

Yea, an opinion at last! So you like the V-6 sounding exaust systems for your pony. Of the '05 GT exaust systems I've heard (MagnaFlow, Flowmaster, Borla, Bassani, JBA and Corsa), the Corsa sounds the most like the typical sporty euro 6-cylnder.

Several magazines both in print and web have dyno'd the stock '05 GT and then installed an aftermarket cat back system with no power gains, just higher SPL out the back in in the car. They've said that it sounds louder and that some people may like the new sound over stock but that there was no real additional power (one article showed a 1-2 HP gain but this was too close confirm as a gain), to be found. It's revealing how almost ALL of the exaust system makers claim to be making lots of addition HP and torque and have all kinds of dyno charts to "prove it" but NO print or web magazine has seen ANY additional power on their independant dyno runs!

$700? That's my point, why pay just for sound? Pay for performance, if it also sounds and looks good all the better. For what many of the cat-back systems (which add ZERO horse power), cost you can almost buy good shorty headers and an X-pipe. This combination is known to make power on the '05 GT while it's also been shown that on the '05 GT that cat back exaust alone makes little or no additional power. The '05 GT's stock exaust system is a very good OEM exaust all you have to do is get the exaust into it better. This is where the headers and an X-pipe come in. The stock '05 GT's cast manifold is a solid 4-into 1 plenum log manifold design but this type of maniflold usually leaves something on the table inorder to make engine installation during assembly easier, the '0GT is no exception. Additionally X-pipes clearly make better power and torque then a standard H-pipe crossover design. But even with the best headers, race cats and X-pipe you are not going to make huge HP gains maybe 10-15HP max. even with a ECU reflash. Personally I'm leaving the everything behind the cats stock and focusing on headers and X-pipe with race cats. This is where the power is going to be had in the '05 GT.

 

Hi Getaway,

You don't like something just because it has some design detail that you don't like? IMO that is just stupid. You say you are more interested in performance than sound and yet you are going to eliminate a successful design based on your own arbitrary design criteria? Didn't you learn the principals of the scientific method in elementary school? Good luck making additional power using this apparently faith based process you will need it.

As for your other comment regarding mufflers, chambered and baffled exhaust systems outperform straight pipes all the time. I have seen this happen on the engine dyno while developing the 302 I used in my '66 2+2, actual I think that anybody who has used an engine dyno for development has seen this happen. This has been reported in car magazines for the last 40 years or so. What have you been reading, the Bible? Not that there's anything wrong with that, it's just that the Bible is a poor choice of reading material if you want to make horse power in an automobile engine. It is regularly reported in engine dyno test articles that when large dia. exhaust tubes are run straight out of the headers there is a power loss and that by adding a chambered muffler power is restored.

If you have header and exhaust tubes that are just big enough to flow all that can be passed through and engine at its' maximum RPM and then add a restrictive exhaust system you will likely loose some power. Given the modest displacement of the '05GT's V-8 a dual 2.5" exhaust system should be plenty big enough to flow all that is needed and it's unlikely that adding higher flow pipes or mufflers will improve the power and torque of the stock displacement engine. The formulas used for tubing dia. and length are well known, I have a book that shows it and I've seen it on the web more than once. Given that by all accounts (at least from dyno tests performed by those without a vested interest in the results), there is nothing to be gained from changing the exhaust system I'd say that the stock cast manifold and stock cats are the only real potential flow restrictions in the current '05 GT exhaust system.

Actually I'd bet that on a stock displacement '05 GT, with stock cams that shorty headers with 1.5" ID primaries that are well designed that there will be a power LOSS in the low RPM ranges but more than gain it back in the mid-high RPM range when used with race cats. If you kept the stock cats the lower RPM range would be less affected and the engine will peak sooner at a lower total output level. All of these comments are assuming a re-tune and reflash on a chassis dyno of course.

There is just no magic bullet out there at the moment to increase the power of the engine tremendously these days. The new '05 GT modular engine is just too well done to allow it. I also think that based on what I've seen and done that the most anybody is going to get out of the new 4.6 3 valve without going internally and without resorting to a power adder is really going to be no more than 45-50HP at the wheels. I mean repeatable power, by this I mean that anybody can bolt on the same parts and use the same tune and when compared to a baseline of the same vehicle you will see the same HP gains as the other guys got using standard corrections. This is NOT to say that this will be a streetable combination, I think that limit will be 40HP, period.

Good luck with your engine program.

 

1fastgt when you get your flowmasters could you be so kind and tell me what you think of them. I like to h ear from owners before I buy them.

 

I sure will.

 

Hey All,

Sorry about the rant, I just get all worked up when I see stuff posted that's obviously coming from left field. I'm better now.