98 ta a4 with 2000 year motor and trans. Following mods being installed are:
head/cam (texas speed), ls6 oil pump, elec. water pump, lt headers, ls6 intake with all the goodies (lid, throttle body, etc.), cpu tune, 3500 converter, elec. cut outs on exhaust, 100 shot nos,

hope to reach 450 rwhp without the nos. I have factory rear end 3.23 as of now (out of money) but need more gears i know.

Should i upgrade to 3.73 in stock rear end or just wait and upgrade axle and do 4.10????

Car won't see track much mostly just around town driving.

 

3.73 would be a good choice for you.

Its up to you IMO though. The only reason I have factory gearing is because I haven't got a Moser 9" yet.

If you don't do much WOT from a stop with sticky tires you might be okay. I wouldn't do it though. Crappy ten bolts

Good luck!

 

You'll be lucky to see 420rwhp through an auto with that setup and an LS6 intake manifold.

Your goals are set too high.

With that being said, I second the 3.73 setup.

Mike

 

3.73s in a Strange S60

 

3.73 it is then

Thanks

do you think with that set up i need to go with a different intake to reach 450 rwhp? i don't want to change displacement and i want to keep it naturally aspirated.

Does the auto really rob that much hp?

 

You're going to be hard-pressed to hit 450 rwhp in an auto with a heads/cam setup. Your best bet if you absolutely need to hit that is to go either with a much bigger cam and a FAST 90/90 setup or the same cam and Trickflow 13.5* LSx heads and a FAST 90/90.

Either way you slice it, the FAST 90/90 setup will give you on average around 15-20 rwhp on a 6-speed and slighly less with an auto.

Yes, an auto usually dynos somewhere around 5% lower than a 6-speed car. If you're making 550 BHP with an aftermarket or ported LS6 heads, 23x/23x cam, FAST 90/90 setup, you can expect around 470rwhp with a 6-speed and 440 with an auto..The setup you described probably won't net you 550 BHP, so like I said... you'd be lucky to see 420rwhp.

Mike