Magnaflow 16678 Cat Back Exhaust Problem

[SeaPro]

So I was going to order the Magnaflow package #16678. I noticed the seller had the diameter listed as 2.25'' but Magnaflow shows it as 2.5''. I emailed Magnaflow to see if they made a smaller version, and told them I was putting it on my v8. They replied with this:

"Sean,

Unfortunately we do not offer a complete exhaust system for your 3.9L v8 model. Part # 16678 is compatible with the 3.0L v6 models only and would not be recommended for the v8.

Best Regards,
Cody Spakes | Tech Line Specialist

Opinions?

 

[SeaPro]

Can somebody confirm that this is an error on Magnaflow's end? From what I've read, this exhaust is used on lots of v8s. Anybody?

 

[cammerfe]

Can't tell you the part number of my cat-back Magnaflow, but I'm sure it's 2.5". It's also ten years old. Perhaps they don't make it any longer.

KS

 

[SeaPro]

Do you have a 2nd Gen v8? I've read on here that there were two options at one time. They don't list this part number as fitting the v8, only the v6. It shouldn't be any different from the cats back though should it?

Every website selling this part number show it as fitting the v8 2nd gen, but Magnaflow is saying it's for the v6 only... Ugh...

I just want a louder nice sounding exhaust. I'm torn on whether or not to buy this. Some people are saying it's too quiet. Not looking for straight pipes, but would like to turn a few heads.

 

[cammerfe]

My LS is an '02. Magnaflow exhausts are not silent and not blatty or raspy either. In combination with an intake tube and an aftermarket filter, it's just right.

KS

 

[SeaPro]

Now I'm reading that the Gen2 exhaust setups are less restrictive than the Gen1 ones... People suggest just changing out the Mufflers. This is a tough decision.

There are so many threads covering this but as usual it's impossible to find a direct answer of what to do.

Basically, I want a louder more aggressive sounding exhaust to go with my K&N CAI. Would mufflers alone achieve this? Maybe resonator delete with new mufflers?

The Magnaflow setup is about a 900 dollars with tax.

 

[BCA]

They offer two systems, part #15710 for the Gen I cars that is a 2.25" system and part #16678 for the Gen II cars that is a 2.5" system.

Currently the Gen I system is listed for both V6 & V8 applications, however they only list the Gen II system as fitting the V6 car and I'm not sure why as they used to list this kit (#16678) as fitting both V6 & V8 cars.
Maybe they made a change to the Gen II kit, maybe not. It could just be that the V8 application was mistakenly omitted during a website update.

Here are the LS listings from their 2010 paper catalog.

 

[cammerfe]

BCA, your post doesn't seem to show pipe diameter, so far as I can see. I put a cat-back system on my '02 in '07 and although I didn't measure it when I installed it, I believe it was (is) 2.5 inches in OD. Can you provide enlightenment?

KS

 

[SeaPro]

So I ate the bullet and ordered it anyway. Magnaflow lists 16678 as being 2.5 inch, the seller (and many others) list it as 2.25 inch. The sellers all list it as fitting the v8, Magnaflow doesn't and said via email it doesn't... I priced out doing mufflers and an x-pipe and it would cost me more than what I paid for the entire kit. I'm handy and will modify this if need be, but after lots of research, even if it is 2.25 inch it will be adequate for the v8. Lots of guys running 5L mustangs choosing 2.25, apparently that's more than enough if you don't plan on going forged internals and serious mods. Thankfully for us this will never be the case lol. I'm away at sea for a few more weeks, and have to do the v8 engine swap before I install any of this. Huge amount of work, but the new exhaust (and K&N 57-2562 CAI) will have to be my motivation.

I've read mixed reviews about the 16678 not sounding as aggressive as people would like, but all in all I think this was the best option. Bolt on sounds better than messing with muffler shops and pipe fitment. I'd really rather do the install on my own time and my own dime! Also, picked it up for around $800 CDN, free shipping. Like I said, the mufflers, pipe and x-pipe would easily cost more. I promise to fully document every part of the teardown and install, and will hopefully have video to share if my swap goes well. I need to put my LSV8 motor into my LSV6. The V8 is rotten and not really safe to fix. The v6 is perfect, but it's hard to let go of the extra power.

Thanks for the info!

 

[SeaPro]

Also, some people have a third catalytic converter to pass emissions in California. I've read many complaints of people having fitment issues because of the third cat. I can't recall, but my car was made in Canada so I'm hoping I don't have this problem. Quite sure I don't. It's unlikely, but maybe that's why Magnaflow said it won't fit? More likely an error on their end (hopefully).

 

[BCA]

BCA, your post doesn't seem to show pipe diameter, so far as I can see. I put a cat-back system on my '02 in '07 and although I didn't measure it when I installed it, I believe it was (is) 2.5 inches in OD. Can you provide enlightenment?

KS

KS,
Those are pipe diameters that are currently listed for each kit on the Magnaflow website.

 

[SeaPro]

So I ordered the exhaust and just received this email from the seller...

"The Magnaflow exhaust you ordered doesn't fit with the vehicle you're putting this on. Please call us to source an alternative."

They will give me a full refund because their site was wrong saying it would fit. What I'm having a hard time figuring out why this will not be suitable... From what I can see in the workshop manual, the exhaust for 2nd Gens are the same... Anybody have any info on this?

 

[SeaPro]

I think my problem is whether or not this car has the third catalytic converter or not. Digging through old posts I have come to realize that they did a whole bunch of funny things with the exhaust setups for different years. Some were built with a third converter based on local emission laws. Luckily from what I've read there shouldn't be a sensor on this 3rd converter.

It's crazy how nobody on this forum has posted about this particular exhaust... Lots of non-complete threads on the subject... I think I'll just order it and cut it to fit. I'll document everything.

Those new mustangs are certainly beginning to look good =P