I just finished my version of the ******* Whistler and replaced my cat and muffler with straight 4" pipe. I notice improved response in the pedal and looks like about 3-4 mpg. Had a drone before the intake but for some reason it got quieter with the whistler. for the intake i used the amsoil filter( i think its 6080 but u should check the ****** Whistler sticky) put a 6" - 5" exhaust reducer on that then replaced the other straight section with a 5" i.d. coupler. the accordian hose on the filter fits right into the reducer and i dont even use a clamp. most people dont weld aluminum so its easier to use the exhaust reducer and make the MAS mounting block in steel. i love the results and it only cost me about $100 for the intake and $80 for the length of 4" exhaust pipe.

 

Good luck on really getting any MPG increase from an intake, the OEM intake is oversized and is plenty of air for 450rwhp, mileage benefits are generally in the drivers head.

 

Im just passing on wat my calculator told me. Any decrease in the amount of work an engine needs to make to move the
mass will increase the efficiancy, hence increase HP= increase mpg. I totally agree that pedal pressure is the root of all evil, but if your rig produces more hp, then less pedal (than before the mods)=same hp.
Its simple physics. Some of us just need to feel good ( in the head) sometimes. Thanks for bringing the needle to my bubble party! Btw i added an intake and exhaust.

 

That's just it, the engine has more air than it needs for even 100hp over stock, so at cruise speeds the airflow isn't hindered at all.

The only way it may improve mileage is by sucking in hot air (read all the threads about WAI and ecomodding), but that will increase EGT's and decrease total power.

Are you talking about a real calc, or your overhead?

Looks like your rig is a cali rig, but even still the exhaust benefits are for towing, racing, etc. The OEM flows pretty good.

Not trying to burst your bubble, just keeping from spreading false info. The reason there aren't any other responses to your thread is because most people read these kinda posts and laugh.