I'm hearing that some after market intake manifolds for LS engines (like an '09 5.3L in a GM pickup) generally provides around a 20 HP gain.

I'm considering doing this and then getting a tune to tweak it all out, so what do you guys think is the best aftermarket intake to consider?

 

Personally, I wouldn't, but go with one of the big names, like K&N etc. Less chance of problems. No idea which is the best for performance.

Be wary of the AFM if you have it!

 

I personally wouldn't mess with it.

For me, it's go big or go home ... hate to be that blunt about it, but nickle and diming the "boltons" for a 5.3L in a truck will only provide minimal gains. If I were to do anything, I'd install some nice ceramic coated headers and a true dual exhaust. Other wise, I wouldn't mess with it. A Chevy that has a factory equipped 5.3L is already a pretty good performer in my eyes and it shouldn't be messed with too much.