2.5" or 3" exhaust with factory manifolds?

[Zedeater]

Looking for some advice on some planning this winter for my bone stock 2010 GT500 I picked up in the fall. So far my long term goal for it is just to maximize the power with the stock blower and go with the typical intake/pully/tune combinations down the road. I’m looking at 2 options for the exhaust, both options will be keeping the stock exhaust manifolds in place.

Option 1 – 2.5” Off road H pipe, factory 2.5” OTA pipes, Brand A,B,C axle back mufflers

Option 2 – 3” Off road H or X pipe, 3” OTA pipes & axel back mufflers

Question is will there be any advantage or disadvantage to going with either exhaust option? Is option 1 2.5” piping plenty sufficient for the planned engine mods to breath or would there be measure gains & benefits with the full 3” exhaust even when the factory manifolds are left in place?

 

[RedVenom48]

I think if you were planning on sticking with the stock blower youd be ok with the factory OTA pipes. For your h pipe, go 3.0.

If you even have the slightest inclination to upgrade the blower ( you probably will) go 3.0 all the way.

As for the muffler? Im still rocking the OEM on my 2011. But if you upgrade to 2011+ OTA pipes, you give yourself a few more options for mufflers.

 

[sleek98]

Good video to watch. There is little power to be had but its alot more noise. I took off my 3" catback and put the stock 2.75 back on due to the volume of noise. I cant believe how much quieter it is.

Last time I was on the dyno I put down 680/655 through the 2012 Over the axle pipes and factory mufflers. That was with stock manifolds and a lethal catless H pipe.

 

[NastyNate420]

Good Video! i watch them all last week! ...go 3"!

 

[Robert M]

Looking for some advice on some planning this winter for my bone stock 2010 GT500 I picked up in the fall. So far my long term goal for it is just to maximize the power with the stock blower and go with the typical intake/pully/tune combinations down the road. I’m looking at 2 options for the exhaust, both options will be keeping the stock exhaust manifolds in place.

Option 1 – 2.5” Off road H pipe, factory 2.5” OTA pipes, Brand A,B,C axle back mufflers

Option 2 – 3” Off road H or X pipe, 3” OTA pipes & axel back mufflers

Question is will there be any advantage or disadvantage to going with either exhaust option? Is option 1 2.5” piping plenty sufficient for the planned engine mods to breath or would there be measure gains & benefits with the full 3” exhaust even when the factory manifolds are left in place?

I installed the Shelby/JBA full 3" mandrel bent exhaust system on my 2008 with FRPP shorty headers about 3 years ago, the car is louder than it was with the rusty cast iron log manifolds and the oem 2.5" with Borla 2.5" catback that Shelby had installed as part of my Super Snake 725 upgrade.

The thing that was/is most noticeable to me was how quickly my car now pulls through the rpm range in comparison to the 2.5".

One other thing to look for is mandrel bent piping. If the pipes are not mandrel bent (even around the axle), the exhaust at wide open throttle can only flow as well as the crimped down non-mandrel area(s) of the system. <<This meaning a 2.75" system could have some 2.50" bends and a 2.50" system could be down to 2.25" in some tighter areas.

If you look a the oem Ford piping, especially over the axle, most times those pipes are not the same size all the way around the bends, they are smaller.

I can also say that a full mandrel 3" will fit around the axle without rubbing, bumping or making any contact if it is a quality fitting system and installed properly.



R

 

[Willie]

There are two sayings that are true for most of us here: 1) No matter how fast you are, you WILL want to go faster, & 2) Even if you think you are fast, there is ALWAYS someone that is faster than you. That being said, the first time you add hp, it feels awesome. Months later, that feeling goes away as you become accustomed to the newfound power. Then you want to go faster, again! And on and on.

So do the exhaust once and be done with it...... 3-inches without question. Bassani has a nice bolt-on system, which I installed many years ago. I've gone through a number of muffler changes and configurations on this system, but it still remains on my car. It bolts directly to the stock exhaust manifolds, cats or no cats (they have both), a 3-inch X-pipe, then the rest of the way rearward.

 

[Robert M]

There are two sayings that are true for most of us here: 1) No matter how fast you are, you WILL want to go faster, & 2) Even if you think you are fast, there is ALWAYS someone that is faster than you. That being said, the first time you add hp, it feels awesome. Months later, that feeling goes away as you become accustomed to the newfound power. Then you want to go faster, again! And on and on.

So do the exhaust once and be done with it...... 3-inches without question. Bassani has a nice bolt-on system, which I installed many years ago. I've gone through a number of muffler changes and configurations on this system, but it still remains on my car. It bolts directly to the stock exhaust manifolds, cats or no cats (they have both), a 3-inch X-pipe, then the rest of the way rearward.

That is a fact!! and the wallet can get thin quickly once this cycle begins.

It is like an addiction.........




R

 

[ShelbyGT5HUN]

Any ground clearance issues with the 3", on a lowered car?

 

[Willie]

Any ground clearance issues with the 3", on a lowered car?

Nope. I have FRPP lowering springs. Just have to be slow on speed bumps.

 

[Robert M]

Any ground clearance issues with the 3", on a lowered car?

I have no issues. I may have a picture from the rear looking straight forward under my car with the 3". Let me check tonight.




R

 

[Catmonkey]

I'd split the difference and find a mandrel bent 2.75" exhaust system for the 2011-2012. I have long tube headers with the 2.75" system and it's loud even with the stock mufflers. There are no stock 3" mufflers.

 

[Zedeater]

Thanks for all the comments, I'll plan to go with a 3" system from the manifolds back. At a glance it looks like Bassani as Willie suggested & Magnaflow both offer complete 3" full systems so that will be the short list unless there are others out there I didn't see. I'd like to get the whole system all from one manufacturer instead of piecing it together from various brands.

 

[Willie]

Catmonkey raises a good point. There is basically no 3-inch muffler choices except the ones that come in the catback kits. So what would you do if you install one of these catbacks and don't like the tone? Too loud, too raspy, drone.... so many ways NOT to like an exhaust. So are you up a creek? Not exactly. I'll use myself as an example. I now call my Bassani my Frankenstein exhaust system. It's been through so many changes with different cats, mufflers and also muffler PLACEMENT. The only thing that's remained the same is the Bassani x-pipe. I even had 3-inch in/out 4x9 Magnaflows.... did not like the sound. What I have now is the best for me. I have a pair of 3-inch in/out chambered mufflers (69 Z28 option) in front of the axles and a pair of 3-inch in/out resonators in the stock muffler location. Absolutely love the sound and also the uniqueness of the complete system.

 

[Robert M]

Here is an under view of my Shelby/JBA 3" mandrel system..............

Since the full 3" system weighs more than the original 2.5" I also added the 2007 only GT500 transmission cross member which has exhaust hangers. This was a nice add to support the system in the mid area instead of all of the weight hanging on the exhaust manifold studs and the rear/muffler hangers only.

The 2007 GT500 cross member........

Unfortunately Ford does not sell the exhaust hangers separately. The 2008-up cross member does have the provisions for them but they are not there from the factory.

R