I have a 2000 Sierra 5.3 with all the standard bolt-ons but long for more power. I am considering a head upgrade. If I stayed with less expensive factory units would the LS6 heads be a good choice if they were tuned up a little first? Any other suggestions? Also, I understand they use a D shaped exhaust port vs. a an standard oval. Is this an issue for headers meant for the standard 5.3 heads? The 2nd part of this is related to the intake. Should I also swap the intake for something from a 'vette or f-body or ...?

 

heads + no cam for them = <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />

do you want more power or just to get there quicker? do a converter/transmission build. 2nd gear will fail anyway so you might as well get that over with.

have you done any computer mods? that will help quite a bit too.

if you want to stick with the heads, look for a reputable builder locally if you can, the head cores aren't that expensive. new 6.0 cores are going to cost me $400 before work. the ports are the same too.

 

That answers a lot of questions. My bolt-ons are a K&N FIPK kit, MAFS, 80mm throttle body with coolant bypass, Bosch +4s, Taylor wires, Hypertech power programmed and a Gibson Super Truck cat back. I have a set of Gibson shortys waiting to be installed.

Sounds like I will just clean up the intake and heads. I am worried a little about value float. Is it worth it to upgrade the rockers and springs? I also have been looking at the Yank converters and modulators as well as Jet's tranny build kit. Any comments?

...and what with the "2nd gear will fail anyway"? I hadn't heard that before.

 

Go with a Yank.

Dont mess with rockers. If you are worried about valve float, get some strong springs. A good cam, .030 milled 5.3 heads with larger intake valves, and comp 918 springs will be a good mix.

 

LS6 heads will bolt on but are not the best choice for a 5.3,they have larger chambers and are more expensive than the stage1 or 2 heads offered by some of the site sponsors,and will not in stock form make as much power.

 

Your stock truck will make more power than an LS1 intake and make more power than the LS6 intake in the rpm range we run our trucks.

 

Don't know what bolt-ons you have but if you have the money to drop into heads, I'd suggest getting your heads ported, throw in a cam, and get a nice stall converter. This will really wake up your truck's power. If you don't have long tube headers, they should give you a nice improvement also.

 

the second gear issue, at least mine, is the second gear clutches. i burned up almost every one of mine. i have heard others talk about 2nd gear failing but don't know what their issue was.

if you are afraid of valve float, just get some corvette springs. how many r's do you intend to turn this thing anyway?

 

Depends but 7-8 grand. I am always pushing the red line now and just want to keep things inone piece.