possible exhaust swap

[DDean]

Kinda wanna ditch the flowmaster 40. I like the sound but as everyone knows they start rusting which mine already has. I've been considering for a long time the Gibson Super truck Exhaust, my question is more about pipe size. It's the factory 3 inches in I don't remember what the shop did for the pipes leading out. Would 3 inches out be to much for 4.7? What is a good recommendation.

 

[89gtcs]

I wouldn't go over 2.75" unless your engine is modified and pushing over 300 hp. Otherwise you'll just shift your peak torque into a higher RPM range (where most of the time you won't enjoy it)

 

[hemihustlin]

Well if it comes from the factory with 3" i dont believe thats excessive.

 

[DDean]

My concern about exhaust stims from performance after the install of the FM40. When I drive normally I push in the gas, rpms raise for a second and drop down, truck continues to drive and no sign of it ever dieing but it just sounds bogged down and it's noticeable in the exhaust tone as well, sounds weak. Before the exhaust this sluggish bog down I speak of didn't exist and if it did, I never noticed it. Anyone think this is related to the FM40? Or could it be something else. Drives me nuts cause the only way to avoid it so my truck doesn't sound like **** is give it a little more gas when I take off from a stop. It only does this when the truck moves from a complete stop or is going slower than maybe 10mph. I wish I could be more descriptive.

 

[xb1230]

The lack of expected restriction at the PCM level could cause this.

I'm throwing something on the table here as I am not sure but could it be a Torque converter issue? Just giving ideas here, really not convinced this is relevant but the issue description almost sounds like the TC is not picking up fast enough... Or could it be a Tranny pressure pump problem?

Am I totally in the left field or could this make any sense?

 

[DDean]

I honestly don't have a clue, hoping for more responses

 

[RonJon '06]

I wouldn't go over 2.75" unless your engine is modified and pushing over 300 hp. Otherwise you'll just shift your peak torque into a higher RPM range (where most of the time you won't enjoy it)

^^This. If they used too large a diam tail pipe and your exhaust velocity is too slow it can cause you to lose low end torque. Kinda sounds like what you're describing.