I would say they're worth it as long as you find a cheap set as mentioned above. Look at the difference in power between the LQ9 and the LS2 as a good example. its a 50 HP difference. You can credit the intake for 10 of that, the cam for MAYBE 15, and the heads for a solid 20-25. 20-25 HP for $300 is definitely worth it in my opinion, especially when that's power that would be had across the board.

Everything I have seen shows the 243's slightly out flowing the 317's as well. I know its the same port design, but I think the better combustion chambers of the 243 allow for more high lift flow. That means the power difference would be exaggerated when you're talking about a custom cam with .600 lift.

 

Whats your 5.3 now, 9.5:1? I wouldnt drop it any lower. You're just going to make it a turd out of boost.

 

D: You got a point! Thanks for pointing that out

 

I say it worth it go for 243

 

i have 243's on my tahoe and the power increase negated the drop in compression. so it feels the same if not a touch better than stock. but in boost its a whole different story.

 

to many 's in here .

In stock form there gonna flow roughly the same. You would be better off saving your money or getting a ported set of heads as desert1500 mentioned.

 

i put the 243s on my lq4 with a 226/226 cam and loved it. made 396 rwhp and 458rwtq threw a loose converter in my 2wd rcsb i would say hell ya there worth it thats my 2 cents