guys with Mac LTs...

you mean like from the factory?

no, i mean like how much did the LTs throw off the AFR before you tuned for the LTs? was it less than a point of difference? i know a tune is not needed for the LTs in most cases, but i was just wonderin about how much change in AFR i'd be looking at in the most ideal scenario

my friend needed a tune after BBK LT and o/r x

Scott2001GT said:

my friend needed a tune after BBK LT and o/r x

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like did he NEED it cause his AFR was unsafe or did he get it to squeeze out all the HP possible?

what i'm asking is will my AFR be unsafe to the point that i can't drive it until i get it tuned? i've got no problem driving it liberally for a couple days, i just want to be able to get to my tuner without putting the car on a trailor

The A/F is going to change but it's only going to be a few tenths of a point. So, yes you'll be fine to drive it for a little bit until you get a tune. It's going to throw a CEL, probably. So order a tune for them and you can drive it until you get it. Unless you've got a tune that's already on the ragged edge you'll be fine.

NastyStang113 said:

The A/F is going to change but it's only going to be a few tenths of a point. So, yes you'll be fine to drive it for a little bit until you get a tune. It's going to throw a CEL, probably. So order a tune for them and you can drive it until you get it. Unless you've got a tune that's already on the ragged edge you'll be fine.

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okie doke. that's exactly what i was wanting to know. i'm thinkin i should just get a mail order tune since i won't be going home until the 3rd. how's vmp? what's their turn around time like?

VMP is definitely a good choice, you won't be disappointed. Turn around times are pretty good, too. If you email Justin, he can give you an idea on when he can get it done.

wow, some MACs shipped?

I dynoed mine before and after. The A/F went from from 12.6 to 13.4.

Mine was never tuned after putting them on. Brenspeed did my email tune and tehy told me there's no point in a tune for headers. I don't know my afr, as I've never had it on a dyno, but it's been like 10k miles since I put them on and I've never had any problem.

Marc S said:

I dynoed mine before and after. The A/F went from from 12.6 to 13.4.

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Hard to believe..

I would not have thought the A/F would have changed that much either because the HP gain was not very impressive.

What kind of headers? Any graphs?

Mac L/T and their O/R prochamber. I gained 11 HP at the peak and lost 2 ft pounds of tq at the peak. However, between 2900 and 3700 RPM's I picked up 37 ft lbs of tq and the tq curve is much flatter. At 6350 before the headers I was making 215 ft lbs and afterwards I am still making 245 ft lbs at 6350. My results showed a bigger overall improvement in the tq curve and not the HP curve. I am sure the loss of tq at the peak is due to the larger primary tubes. But, I have a Kenne Bell supercharger that I am installing this month so that will mix my tq loss.

Do you have a graph that you can post up?

I can do that, there in my shop, I will get them tomorrow.

I dunno about you, but I'd take a big gain in average torque over a gain in peak horsepower anyday. That's kinda odd, mine "felt" like it lost a lot of power down low. But ass dyno's are misleading. My car still feels slow to me, though it really isn't. I mean, it ran 13.1 on street tires so it isn't "slow", but it feels slow to me. I must have a Mustang brand ass dyno or something. I just hope it doesn't feel slow anymore after I supercharge it next year.

UrbanRedneck said:

I dunno about you, but I'd take a big gain in average torque over a gain in peak horsepower anyday. That's kinda odd, mine "felt" like it lost a lot of power down low. But ass dyno's are misleading. My car still feels slow to me, though it really isn't. I mean, it ran 13.1 on street tires so it isn't "slow", but it feels slow to me. I must have a Mustang brand ass dyno or something. I just hope it doesn't feel slow anymore after I supercharge it next year.

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To me a 13.1 is impressive on street tires!!! great accomplishment man!

Thanks Ian. It had more in it too. I only got 2 runs that day, so I had no practice. I was slipping the clutch out at 2900ish with zero tire spin, 1.8 60'. I think I coulda got more agressive and made a 13 flat. We'll see this summer.