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Discussion Starter #1
I was wondering what your take was on a couple of things...

When i had my '99 GT, i had a bunch of bolt ons but one that gave me the most "seat of the pants" performance was the underdrive pulleys. Also the first thing i did to the car was replace the stock mufflers with Mac Flowpaths. Later on i ended out swap'n the whole thing out and going with 2.5" catback form SLP. What a mistake that was. It was as if i LOST power, mainly at the bottom end. Its like the thing wouldnt even get off the line to save my life.

So, do you think that i would have the same effect with the pulleys on a 289 like i did with the 281pi or would it be a waste of money?

Also, does anyone know why i would looses power when going to a catback system? And should i leave my stock 2" exhaust the way it is (stock pipes with Autozone type turbo mufflers) or go bigger and whats the biggest i should go?
 

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If you have dual exhaust the biggest you should go with a 289 is 2.5 inches unless its stroked or making a ton of power. A stock 289 only needs 2 in pipes i think. 2, 2.25, or 2.5 should be all be fine. If you go to big you loose some low end torque.
 

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I ran 2" straight duals with sonic turbos on my 66 and it ran and sounded great. If you haven't already, switch to an electric fan, go with a modern a/c compressor. In addition either UDP or switch to a serpentine belt setup. IMO this is the best way to go. The factory fan and a/c compressor rob a lot of power.
 

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Discussion Starter #4
yeah about that a/c compressor... can i just get a different belt and bypass it all together, like in the winter months or does it only rob the power when its on? I mean all a/c systems do that, but does one extra pulley make that much diff even when off? And what do you mean "modern" compressor? Electric fan huh? There are a few brand out there. Whats the best and what size do i need? I dont even know the size of mine now to be honest.
 

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yeah about that a/c compressor... can i just get a different belt and bypass it all together, like in the winter months or does it only rob the power when its on? I mean all a/c systems do that, but does one extra pulley make that much diff even when off? And what do you mean "modern" compressor? Electric fan huh? There are a few brand out there. Whats the best and what size do i need? I dont even know the size of mine now to be honest.
The a/c would take some power to turn even if it is off. It just takes more when it is turned on. You could use a different belt and just not put it around the a/c pulley the only problem would be that you wouldn't have a/c.
 

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You can run a short belt and bypass the a/c. Dallas Mustang has kits to convert to electric fans and Sanden a/c compressor. You may want to check Sacremento Mustang, Texas Mustang, etc... for the best price. The factory Tecumsah robbed a ton of power on my 66 so I just took the a/c belt off when I needed the extra horses. I never got a chance to update the pulleys and compressor on mine, but plenty of people here have and love it. Dad and I are getting ready to replace the whole a/c system on his 69 ragtop which will be using the Sanden compressor. While doing the conversion, I am going to try and persuade him to convert to an electric fan.
 

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Discussion Starter #7
Ok well it is only a 2" piping so i guess thats fine for what i have. I plan on adding POWERHEADS (oem heads with larger valves and ported) I think that should take care of my hunger for power for now, but in the mean time, i came across this...

http://www.virginiaclassicmustang.com/mustangparts/shop/item.asp?itemid=EH186

Do these things honestly do anything or is it all hype? I mean if it does then you cant beat 50 bucks right?
 

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X-pipes are going to add more power but take away some of your sound. So yes, they do work. I've got 2.5" pipes and I'll be adding an X to them when I get home.
 
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