Have you had it tuned with the cut out open? To my understanding, to take full advantage of the cut out you must tune with it open. Just a thought.

 

my 00"rcsb has a bolt on 5.3l stock motor stock stall. Just bolt on's with 4.10 gears and mine runs faster with the cutout open in every area.
I tested it multiple times at teh track. Closed, full track open,launch then open,2nd gear then open.
In the end open the full 1/4 netted me the fastest times in 60ft,1/8and 1/4.
Normally netting me overall at least a full tenth evertime i open it up.
So with a stock stall i can only leave at a max of 1800rpms and i still get benefit from it. In the end 13.7@99 with it open. 13.8@98 with it closed.




Also my truck is tuned like donkeydick lol. Just FYI for everyone.

 

always remember the track is the REAL DYNO GOOD LUCK

 

it was just on motor.no n20.i never dynod my truck with n20.
also i would feel it alittle weak with it open.thats y i never took it off.at the track i an the same time when it was open or closed

 

You have to tune for the lower backpressure or you can actually lose power. I did a GTO tune for a friend with and without his cutouts open. He gained 20RWHP with them open over the top numbers I could achieve with them closed.
You also have to remember that if you tune for the open exhaust when you put a cork in it you will likely lose power for your everyday driving. For my GTO I had 2 tunes ... 1 for open and 1 for closed because I couldn't figure out how to make them both work simultaneously at that time.
I intend to borrow a great idea from the newer corvette exhaust. A vacuum actuated exhaust cutout so it is subtle in everyday driving but when you floor it you can have the benefit of the open exhaust similiar to how the newer corvettes work and it should be tunable.

 

+1

 

i too have been looking at getting cutouts for my 6.0 denali. As i understand it, i would need two of them right (what size) and should i put them before or after the cats?

 

yea i lost 20ftlbs of tq when i dynoed my old truck with a cutout, but gained like 2 HP lol

 

I have one cutout after the cats and it makes a huge difference with the 6.0. But I think the denali has stock dual exhaust so you can put a cutout after each cat and gain even more. If you put them before the cats mayube you might lose lowend, i dont know.

 

This past weekend with the same tune for closed and open cutouts.
closed 60' 1.60,s
open 60' 1.59's and picked up about .10 in the 1/4 mile.
I had to run true street through mufflers and could run open cutouts in the LSX class.