IDK honestly you can probably grab an extra 20HP out of the engine, but really you wouldn't wanna do more without tranny work.

 

I second that....You could probably pull 10-20 HP with induction and exhaust...That should cost you about $600 give or take...The nice thing about these mods is not only will you gain a few HP, your fuel economy should go up 1 or 2 MPG.

 

I wouldn't say with induction and exhaust only...

probably going to need the throttle body spacer, and ZZP has LSX rockers now.

 

Chibiblacksheep is right, if you want 20 HP, chances are you will need the throttle body spacer rockers too....

I would say that induction and exhaust is only good for about 10 HP...although the manufactures will claim WAY more...but I think about 10 total HP is more realistic for both induction and exhaust.

 

They're always gonna do that.

If you take a car that has some crazy engine mods, but a completely stock exhaust, and then upgrade the exhaust...then you're going to see much bigger gains than if you took a stock engine and upgraded the exhaust.
Manufacturers/vendors can (and do) exactly that.

Even ZZP....usually they're honest, but look at the listing for their 3" cat-backs.
They're claiming that someone gained 85hp just from upgrading the exhaust.
Did that really happen? Likely.
Was it a completely stock car with a well-functioning exhaust before the upgrade? Not likely.

-Riggs.

 

you could always run a 100 shot on it. theres a guy on the other forum that rickakated posted thats running one. theres your 400 horse. didnt run 10k and didnt blow his tranny up. downside is you gotta refill the bottle.

 

why does my name make you sad, i have a bad imagination and this name is easy for me to remember

 

While I'm not an expert on the LS4, it seems like you'd be talking outside of the range of bolt ons.

I would think you'd need one of these:

-turbo
-csc
-nitrous
-ported heads + cam

 

i think it makes him sad cause of dimebag? and your right it is out of the range of bolt ons.