4 steps in specifying the best merge collector
Burns Stainless Merge Collectors are highly respected by many engine builders including NASCAR, and are widely used by champions in NHRA, IMSA, FIA-GT, and V8 Supercars. Here are 4 steps in specifying the best merge collector for your application.

Burns Stainless Merge Collectors (Header Collectors) are custom engineered for each application using our proprietary X-design parametric custom exhaust design computer program. Merge Collectors combine high flow and high velocity to increase and broaden an engine's torque curve all the way to the horsepower peak and beyond.
Our products feature the highest quality fabrication and TIG-welding. Each is completely hand finished inside for proper flow.

merge collector cutaway

For drag racing and similar applications where a tailpipe is not required, megaphones fitted with reverse cones are invariably the best option. They produce maximum horsepower and maintain the highest and smoothest torque curve. Megaphones also offer the highest potential power past the peak without compromising the lower end of the power band on well-developed engine combinations with optimally short-header tube lengths and a well-chosen collector outlet diameter. For applications which require tailpipes, a NASCAR-style transition (long or short) and ring is normally recommended. If you are unsure which style is best for you, please call to discuss your specific application.

Here are some common collector outlet options.

To specify collectors for your application, we need to determine these 4 basic parameters.

1. Inlet type-number of primaries* entering the collector and the outside diameter (OD) of your final header primaries. This is where the collector begins. *Collectors are available in 2, 3, 4, 5, and 6 into 1 configurations.
Merge collector Diagram
2. Collector Outlet Diameter- determined by our X-design program. There is no standard outlet size, each collector is based on the engine’s specs. V-Band Flanges are typically added to Turbo Collectors.
Merge Collector Diagram
3. Style of Outlet- Shown are five of our most common merge collector outlets: Straight extension, V-Band Flange, Short or Long Transition, or Megaphone-Reverse Cone.
For optimum flow, the collector exit should be larger than the collector outlet size and is the reason for the distinctive “hour glass” appearance of merge collectors.
Transitions are normally used in applications with tailpipes, or where a short collector is required. If the tailpipe is to be butt-welded to the collector, a tailring is not necessary.
Merge Collector Diagram
4. Final Outlet Diameter- designed to adapt to your existing exhaust.
A tailpipe ring (tailring) is described by its outside diameter. It slips inside your tailpipe and is normally 2" long.
If you plan on a megaphone, a reverse cone is highly recommended.
Merge Collector Diagram
Megaphone tubing is used, especially with a reverse cone, for maximum peak horsepower and power bandwidth.  A Megaphone with Reverse Cone has the added dimensions of; taper, Max OD, Outlet OD, and Overall Length. 
Merge Collector Diagram

Each of these is available in 2, 3, 4, 5, and 6 into 1 configurations
5 into 1 and 6 into 1 collectors are special order items.
Please call for info.

Now that you are armed with this information, give us a call to help you specify the best merge collector for your application.  (949) 631-5120 d


Rod Brace

4 into 1 1.75 to 4" titanium can you supply?

jerry arnett

I have a 408 ford 2" to 2 & 1/8" step headers rpm range is 7400 to 8400 should I use a 3 1/2 “collecter or 4” , I have 34" tubes , thank you



I’m a newbie to the motorcycle worls, and Im trying to build a 4-1 Header/Muffler. And I need to buy a merge collector that would fit my headers to a muffler.

It’s a CB 500 Four 1974.
As far as I know from research, the measurements to connect the headers using a merge to a Generic Muffler I’m buying are:

Header Pipe:

- 1.250" outside diameter = 32mm (at least it should be these measurements? The CB 500 Four already has the headers. All I need to buy is the merge collector and the shorty muffler I chose, link below).

Muffle “Shorty”:

- Total Length: 17.5" 
- Inlet OD: 1-3/4" (44mm)
- Outlet OD: 1-5/6" (46.5mm)

So I guess I need a Merge collector with 4 32mm inlets to a 44mm Outlet.

Could any of you please enlighten me on what are the correct measurements I should look for, and where to buy one at a reasonable price?


Vista Grande Motorsports

Need qty two x 3.5” into two 2” or 1.75” collector in titanium. Can you supply ? Thnx !

Charlie White

Do you make a collector with 2 3/8 or 2 1/2 inlet and 5” out ?

Dave Hughes

I have a 632 EFI engine with MBE Big 9 heads.
1315 hp 1000ft lb
Need a custom header kit in stainless
Stepped 2 3/8 to 2 1/2
Merge megafone reversed collector 4.5
Want maximum h.p for 69 Camaro door car to
run Top Sportsman

Bill Stevens

I have a 588 in wedge Mopar tube car making about 1050 hp on gasoline. Have now got step headers with regular collectors. 29: primary’s and 4.5" collectors. The Step primarys are 2.25 and then 2.3/8. \What would I see changing to your merge collectors on this car. Also, would I need to shorten the primary pipe a couple inches/ Thanks for you assistenace. Bill Stevens in Marylnad

stan susman

Boys, any advantage gained on a twin cylinder engine if so any way to guess a % ? it only turns 2700 rpm.
Maybe I’ll just get me some meaty Joe’s

Burns Stainless

We sell 15-degree bends that can be cut and welded into a collector – but it is not a kit per-se. We do have header kits for crate motors and we can put together custom header kits including flanges, tubing bends, and collectors

Freddie Horn

Do you all sell merge collector weld up kits ?
I’ve never heard of a “weld-up” merge collector kit but was told you all might have them.
Freddie Horn

Leave a comment

All comments are moderated before being published

Our Mission

To offer you the best selection of race quality parts. Relentless innovation in exhaust technology isn't just a tag line, we are always improving, advancing, and refining what we offer.