Secondary cat delete question

[JohnEastvold]

Do secondary cat deletes yield much if any hp? Those are the only thing left on my exhaust system (have test pipes, resonator delete and muffler deletes and yes its crazy loud and raspy but i dont mind) and looking to remove the secondary. I wont if it wont get me any extra power.. input? I dynoed 384whp SAE and have 2 parts left to gain close or over the 400whp (SAE) club N/A. Intake is one, i still have oem filter and secondary cats. Think it will gain anything?

*down the road i will be adding a muffler system. Not sure what yet*


I have searched around for people on secondary cat deletes and dynoing after but didnt find too much. thanks.

[Mvy]

I wouldn't expect much from secondaries. I ran some dynos with stock cats, with high flow cats and with test pipes on the primaries. I got approx 30 hp out of the straight pipe vs stock. Interestingly, same test results were achieved with high flows as with test pipes, so I opted for that. Much better smell wise with the high flows.

[JohnEastvold]

Originally Posted by Mvy

I wouldn't expect much from secondaries. I ran some dynos with stock cats, with high flow cats and with test pipes on the primaries. I got approx 30 hp out of the straight pipe vs stock. Interestingly, same test results were achieved with high flows as with test pipes, so I opted for that. Much better smell wise with the high flows.

Oh cool, i dont mind the smell since im running E85 N/A haha. But just trying to really squeeze everybing out of this motor its got hidden haha. But yeah if u had the same results might as well keep them on

[Evolve Automotive]

you removed the primary cats which do the most gains. Secondaries will just make it louder.

[tom @ eas]

Originally Posted by JohnEastvold

Do secondary cat deletes yield much if any hp? Those are the only thing left on my exhaust system (have test pipes, resonator delete and muffler deletes and yes its crazy loud and raspy but i dont mind) and looking to remove the secondary. I wont if it wont get me any extra power.. input? I dynoed 384whp SAE and have 2 parts left to gain close or over the 400whp (SAE) club N/A. Intake is one, i still have oem filter and secondary cats. Think it will gain anything?

*down the road i will be adding a muffler system. Not sure what yet*


I have searched around for people on secondary cat deletes and dynoing after but didnt find too much. thanks.

Deleting secondaries offer little to no gains for the cost involved, unless bolting on a catless X-pipe. Mufflers are non-restrictive, we've had 700whp Stage 3 ESS cars on the dyno with stock mufflers.

Look into intake, underdrive pulleys & lighter wheels to inch you closer to the 400whp mark.

[JohnEastvold]

Originally Posted by tom @ eas

Deleting secondaries offer little to no gains for the cost involved, unless bolting on a catless X-pipe. Mufflers are non-restrictive, we've had 700whp Stage 3 ESS cars on the dyno with stock mufflers.

Look into intake, underdrive pulleys & lighter wheels to inch you closer to the 400whp mark.

Cool thanks! Ya i have MS underdrive pullys, just need an intake looks like! Do u guys reccomend drop in filter or whole elbow too?

[JohnEastvold]

Originally Posted by Evolve-US

you removed the primary cats which do the most gains. Secondaries will just make it louder.

Yeah true and louder isnt anything my neighbors want haha

[Evolve Automotive]

Originally Posted by JohnEastvold

Yeah true and louder isnt anything my neighbors want haha

What are you looking to achieve overall?

[JohnEastvold]

Originally Posted by Evolve-US

What are you looking to achieve overall?

at or above 400whp i baselined 340whp SAE and most recently 384 SAE, last thing i can think of is an intake to pull out a tad more power since i have an 08 with factory intake.