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**Dominic Toretto** · 11-07-2013, 01:00 PM

Has anyone noticed a flow chart or have definitive evidence that the Boss heads are worth the upgrade to over the factory GT heads? Curious to see how they would effect power on a standard GT with the regular manifold.

P.S., if this has been explained already on here, shoot me in the face.

-Alex

**TrueStreetTim** · 11-07-2013, 04:47 PM

BOSS are mildly ported and flow roughly 5cfm more per cylinder than the GT. Valves are a bit different and the spring rate is a tad better. Worth it to purchase them as a performance upgrade? No. Not IMO.

If someone were interested in something like this I'd recommend putting that money into cams which I think is a better upgrade than heads alone.

**Dan12GT** · 11-07-2013, 05:17 PM

^^^ This

**Dominic Toretto** · 11-07-2013, 05:27 PM

Excellent response, thanks Tim. I was just looking over prices of NA upgrades. I did notice the cams. I would think though that a cam would perform better with the Boss heads but not sure how much better. Any takes on that?

-Alex

**wbt** · 11-07-2013, 05:30 PM

No need for this info.

**KungFuHamster** · 11-07-2013, 06:21 PM

Originally Posted by wbt

There are a few other differences and advantages to the Roadrunner head over the Coyote:

1. Larger exhaust valves.
2. Lighter exhaust valves.
3. CNC ported.
4. CNC'd combustion chambers.
5. Clearanced for running larger lift cams.
6. Different alloy that provides better cooling.

IMO if you are looking to switch over to Boss heads I would go with the CJ cam's at the same time to take full advantage of the port work and the CJ intake to compliment it. While you have the front cover off, billet oil pump gears and Boss timing chain tensioners.

Should have no issues with a reliable 8K RPM N/A motor at that point.

what is the main difference between the stock 5.0 and Boss timing chain tensioner?

**TrueStreetTim** · 11-07-2013, 06:46 PM

Originally Posted by Dominic Toretto

Excellent response, thanks Tim. I was just looking over prices of NA upgrades. I did notice the cams. I would think though that a cam would perform better with the Boss heads but not sure how much better. Any takes on that?

-Alex

If your not worried about the small peripherals that come along with the BOSS heads, porting your stockers is a slightly cheaper, much higher flowing option.

**wbt** · 11-07-2013, 07:55 PM

No need for this info.

blownaltered · 11-07-2013, 11:23 PM

Originally Posted by wbt

There are a few other differences and advantages to the Roadrunner head over the Coyote:

1. Larger exhaust valves.
2. Lighter exhaust valves.
3. CNC ported.
4. CNC'd combustion chambers.
5. Clearanced for running larger lift cams.
6. Different alloy that provides better cooling.

IMO if you are looking to switch over to Boss heads I would go with the CJ cam's at the same time to take full advantage of the port work and the CJ intake to compliment it. While you have the front cover off, billet oil pump gears and Boss timing chain tensioners.

Should have no issues with a reliable 8K RPM N/A motor at that point.

Seems like putting a blower on it would be cheaper. Would get more power out of the blower as well

**Dominic Toretto** · 11-07-2013, 11:49 PM

Originally Posted by blownaltered

Seems like putting a blower on it would be cheaper. Would get more power out of the blower as well

Seems like adding two bottles of nitrous would be cheaper. Would get more power out of nitrous as well.

-Alex

**wbt** · 11-08-2013, 01:25 AM

No need for this info.

**Dominic Toretto** · 11-08-2013, 09:15 AM

Originally Posted by wbt

It's a lot more difficult to go fast N/A vs. slapping a power adder on. It all comes down to goals.

Fast is relative. I'm good with how fast the car is stock. I'm not looking to build something to be faster than everyone else's car. And basically this thread is just about information gathering. For those people that ARE looking to be the fastest car on the track they might want to know information about both sets of heads as well

-Alex

re-rx7 · 11-08-2013, 10:42 AM

Good info in here.

**Grandpa** · 11-08-2013, 10:56 AM

Originally Posted by blownaltered

Seems like putting a blower on it would be cheaper. Would get more power out of the blower as well

I agree. For the return on the dollar and ease of making power boost is the way to go in my opinion.

These Coyote parts are ridiculously expensive it's mindboggling that it's a Mustang. Reminds me more of the Vette tax than a Mustang! lol. For me, the return on these heads just wouldn't justify the cost for MY goal for my car.

Plus, I LOVE boost!

Originally Posted by Dominic Toretto

Seems like adding two bottles of nitrous would be cheaper. Would get more power out of nitrous as well.

-Alex

LOL, never owned a nitrous car before have you?

Originally Posted by wbt

It's a lot more difficult to go fast N/A vs. slapping a power adder on. It all comes down to goals.

It's certainly far more difficult. Driving ability, suspension set up and weight become far more of a concern. I'd rather take the easy road and just throw boost at it. And of course I couldn't remotely care less about chasing an ET anymore. I have to ignore it and just have fun with the car otherwise it will become a weekly obsession to chase those magical ET whoring out the car and wasting a LOT of time at the track over times that really mean nothing at the end of the day. I look back at that time, I learned a lot, but I can't say I enjoyed it a lot because I obsessed over it so much. It became work instead of just having fun.

re-rx7 · 11-08-2013, 11:02 AM

I loved building the Na hondas as funny as that sounds. To build a fast NA car you really have to know your shit and that particular car to get every ounce of pony!