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Discussion Starter #1
Hey guys I just kinda wanted to see what people thought of the IRS. I have the opportunity to get the complete setup for $325, but is it a direct swap, will I run into issues with stuff like wheel hop, is it really worth it considering the suspension stuff costs more, how much power they can take? Any info would be great. I finally found a semi local guy that can get me that or a solid for less, maybe even with gears.
 

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IRS is awesome,
after you dump some serious coin into it.
 

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Discussion Starter #3
How much are we talking? And like what? You're exactly the guy I was hoping would come in on this. Cause I don't think $325 is too bad for it.
 

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MOAR BOOST
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My buddy has IRS on his six. He likes it, but they hold less power than a SRA. Not sure what is involved in the swap exactly. Your car will definitely be a less bumpy ride with it, but you're also looking at more weight and probably an easier rear end to break than an SRA.
I can ask him about it if you want me to.

Just note that you will also need to get an IRS catback exhaust...the regular exhaust won't fit
 

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Discussion Starter #5
Good point, I'm not changing the exhaust too. Nor do I want to really have to dump more money into it than I have to to get it to hold 500 or so.
 

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MOAR BOOST
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Yeah, you're probably looking at atleast 300 to get an IRS catback to go with it.
Found an EGR mount for that windstar btw. Thumbs up.
 

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Getting rid of all the rubber from the IRS is a key point to reducing wheel hop

You can get a complete bushing kit for around 675.00
 

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the only thing that i know about the cobra IRS's is that apparently the 99 is the weakest of them all.
 

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Well to give you an idea....

One guy in town has a kb cobra that was making 666rwhp, he broke the LV5 halfshafts that are like 6-800$ and this is a car with a completely built irs.


Upgrade the busings spend about 650-1000$ doing that, and a brace / diff housing.

And just hope the axle shafts like you :D
 

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Well to give you an idea....

One guy in town has a kb cobra that was making 666rwhp, he broke the LV5 halfshafts that are like 6-800$ and this is a car with a completely built irs.


Upgrade the busings spend about 650-1000$ doing that, and a brace / diff housing.

And just hope the axle shafts like you :D
yeah that would get expensive real quick.
 

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King Trashmouth
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IRS handles awesome.

You will need a new exhaust though, and yes, the 99's were the weakest. One of the added bonus's is that the Cobra axles are geared to 3.55:1.

But at your power levels you shouldn't have to worry. The guys snapping things are 600+rwhp Cobra's, and that's usually launches at the track with drag radials. Not a V6 on street tires cruising around town. I've got a V8 and 245's and I have yet to have a problem, even with agressive launches. In any case good bushings and an IRS brace kit will solve your problems.

At any rate, that price seems like a steal. Just be aware that it could be a MKVIII IRS. The difference is the MKVIII used 28 spline axles vs 31 on the Cobra, and I believe had the 3.27:1 axle ratio, otherwise they were identical.
 

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King Trashmouth
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Well then. What HP/TQ level? It seems to be when you break 600hp/tq that it begins to become a problem.

Not to mention it's important to mention these are typically with twin screw superchargers that are already putting out massive torque numbers down low, versus a turbo which develops peak torque much later. I imagine that turbo launches (save fully spooled auto with a transbrake) would not be as harsh on it as a twin screw.
 

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If you want to have the IRS problem free all you need to do is upgrade subframe bushings, diff bushings, and control arm bushings, good stiff springs in the back and if you break an axle then that when you get a 31 spline diff and oem 04 cobra half shafts
 

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Also I'm in the 350 rwhp range with nitto555 and I have 0 problems with my set up. Check my garage for modds
 

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Discussion Starter #20
Thanks for all the responses guys. And I do know the rear is from a Cobra, the guy is always parting out wrecked Mustangs. And for the record, I wasn't looking to get an IRS, I was just looking for an 8.8 rear to build and this guy mentioned he had a 99 Cobra IRS for $325.

I won't make more than low 400s at most on my TT 6. But I'll put it around 550 next year with the 4.6. So it's something I need sooner or later. A sof now I'm just waiting for the guy to get in a solid 8.8.
 
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