How much gain is a res delete + tubi boxes?

Just curious because I’ve read about some outlandish claims of power gains from these mods on a 456gt. I have the straight pipe res delete and tubi cans. Also, how much would adding hi flow cats gain? And what do they cost? Can’t find much in the way of dyno charts on this car.

 

Would love to hear your exhaust... I have the Tubi cans... but have not pulled the trigger on straight pipes to replace center resonator!

 

If the center muffler on the 456 is the same used on the 550/575 then there is power to be gained as the pipe is crimped down to 2" from 2.25" at the exit of the muffler. Swapping out the rear mufflers is more for sound and weight reduction.

I haven't seen much on high flow cats for the 456/550/575. Would likely need to fabricate some downpipes with high flow cats. This would also greatly increase the volume of the exhaust.

 

Huh, I read somewhere there was a direct high flow replacement that was cheaper than oem also. Maybe discontinued.

 

I like the sound, the car does have a drone now but it doesn’t come in until after 3k rpm and that puts you around 90 in top gear so it’s not terrible for speeds under that. It’s not loud at all with this combo, but does have a bit of a growl.

 

The center resonator was not at all restrictive on my 2003 456M.


Image Unavailable, Please Login Image Unavailable, Please Login

 

Might not look restive but it still is with the perf metal. And there’s a very slight neck that reduces to closer to 2”. It’s barely noticeable. It’s the screen that is causing drag.

 

@Salami any "seat of the pants" torque feel? Or just a slight sound difference?

 

Maybe a little? I dunno. I also went from K&N to oem air filters at the same time so I might have lost the gains there.

 

I’m tempted to weld a tiny crossover tube like 1/2” or less to see if it quells the drone but I’m afraid it will hurt performance.

 

Fabio uses two small crossover/balance tubes on his H pipe. Does not affect hp too much, but makes a big difference in resonance.

 

Interesting. Using two would help stabilize the assembly for sure. Did they do any science type stuff to arrive at that or is it just a shoot from the hip sitch?

 

It seems like it would only take a tiny crossover to kill the drone. Maybe even 1/4” tube or two.

 

Look on Fabio's site and there should be an image of his H pipe.

 

I believe he tried an X pipe and this is where he landed as it resulted in more HP. Some prefer the X-pipe sound from threads I read from years back. Here is Fabio’s pipe.
Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

This is what I was referring to from the 575

Image Unavailable, Please Login