Gibson Headers and 6.5 Diamond Eye Diesel Exhaust on 454

[454cid]

The stock 3" in/3" out cats on my Express van were actually quite restrictive. When I put the Tri-Ys on the Express I swapped out the cats for Thunderbolt 200 cell count metallic core cats and swapped the magnaflow for a bus muffler. ZERO drone from my 350. Almost all of my engine note is intake growl.

What makes you think it was the cats that were the restriction and not the exhaust manifolds?

 

[L31MaxExpress]

What makes you think it was the cats that were the restriction and not the exhaust manifolds?

Because I drove it after the headers went on with stock cats and a Magnaflow. Swapped out the cats and it was too loud towing my trailer in 2nd gear uphill at 4,500 rpm. Which is why the bus muffler went on it. Also the Bus muffler cost 10 rwhp @ 5,500 rpm compared to open cutouts right in front of the muffler.

 

[Christian Steffen]

The stock 3" in/3" out cats on my Express van were actually quite restrictive. When I put the Tri-Ys on the Express I swapped out the cats for Thunderbolt 200 cell count metallic core cats and swapped the magnaflow for a bus muffler. ZERO drone from my 350. Almost all of my engine note is intake growl.

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So it had the dual cats, and they were restrictive, or it was a single 3"?

They might be a little more restrictive than a straight pipe, but I really don't think they're a major power robber. At least I really can't say that I felt an appreciable difference when deleting my cats, which I know is an extremely subjective test.

 

[Sparkysikes]

They've done many test on cats and new they cost no sub 3k hp and very little up top. Bad cats can easily drain 30+ hp

 

[L31MaxExpress]

So it had the dual cats, and they were restrictive, or it was a single 3"?

They might be a little more restrictive than a straight pipe, but I really don't think they're a major power robber. At least I really can't say that I felt an appreciable difference when deleting my cats, which I know is an extremely subjective test.

Dual 3" factory cats. Dropping them probably gained 20 hp. I gained 15-20 gms/sec airflow from 4,000+ rpm when I did the swap. Ceramic core cats are horrible for flow and very restrictive.

 

[Fez_Jet_Az]

Can you guys link me to the bus muffler you are running?

Was thinking about the Spintech RV muffler as an option

 

[L31MaxExpress]

Can you guys link me to the bus muffler you are running?

Was thinking about the Spintech RV muffler as an option

They are offered in many different sizes and configurations.

https://www.summitracing.com/search...hool-bus-mufflers?autoview=SKU&ibanner=SREPD5

 

[Sparkysikes]

Are they quieter than the spin tech? My 6.5 gets fairly loud

 

[Supercharged111]

Mine is quiet like stock with stock cats and manifolds. Should growl a little more with the front half opened up. This is what I have. I combined it with a short extension and a Diamondeye tailpipe and some 1/2" weld on hangers I found on Amazon.

https://www.summitracing.com/search...meter-in/2-750-in?autoview=SKU&ibanner=SREPD5

 

[Sparkysikes]

Yeah I need 4" in and out. My current is a 28" x 7"