I've been searching the forum about upgrading my drivetrain but it is all greek to me. I need something good for 350hp. Can someone break down what parts I need to upgrade my tranny?

Ok, number one thing you are going to hear is erase your dreams of 350hp, you can get there but you're about $23k from it and an Auto tranny won't hold it long. Having said that (you will hear it again from others) Search Infinit3 put together a prototype tranny that is a lot stronger and more effecient than stock, at least it appears to be. He posted a list of parts in one of his posts. If you want to be happy with the Auto tranny then start with a tranny cooler, the bigger the better. Next on our list is a Shift Kit and Stratus Final Gear set. Next up, install a switch, or just cut, on the Orange w/Black stripe wire coming out of the ECU, this is the Torque Reduction mod, I suggest you search it. These are the easy things you can do to our tranny's, everything else is going to mean pulling the tranny out of the car, so be prepared and make sure you want to go this route. Stall converter is going to make the biggest difference, try a 3,200 stall, it's mean, but if you're serious then go for it. I believe that a Phantom Grip LSD can be used on the auto tranny, but not completly sure on that one, search it. The only other thing left is a full rebuild with Kevlar bands and clutches and high pressure pump, and basically everything that Infinit3 did. Other things that will help if this is a drag car (I hope) are Polyurethane/Solid Motor mounts, smaller tires, lightened flex plate, etc. Good luck, I hope this helped. Prepare yourself for the neverending stream of, 'Use the search function' responses, because this HAS all been covered.

I'm not dreaming when it comes to 350hp on our 420a. It can be done...price is not issue for my question to be answered correctly. I also thank you for your responce. It gave me something to start on. I'm looking into the quaife differential with some kind of upgrade TC. So if this gives you something to work with help me from here. Anything else that I would need to do?

get all these parts and your set Transtar High Energy Rebuild Kit - K7200H $193.00 This kit uses the Raybestos High Energy clutches (kevlar)
Transtar Shift Kit - K72908J $26.00 www.naparts.com
Transtar Differential Pin Safety Clips - 72984 $5.00 each
2 needed and any trans shop (even the dealer) These are plates that sit on the outside of the diff and hold the pin in the assembly.
Transar Booster Valve Upgrade - 7208V $15.00 raises the line pressure for better shifts
Alumunim Accumulator pistons - part number unavailable (looking) $15
Phantom Grip LSD - 904 $271 www.phantomgrip.com but(quaife LSD is MUCH BETTER)
2600 Stall converter - $300 Hughes converters (core needed)
or 2800 Protorque High stall converter updated solenoid pack Shifter Solenoid - dealer part (depends on year 98+ use different plugs I think) or Precision International Part Number K31900-6
B&M Trans cooler - $45
Raybestos inline microfilter - $30
Autometer Trans Temp Gauge - $45
Drain plug - $5.00
Mopar Anti-Foam Additive Final Drive gear set Mopar part# 4773275

there are a couple more parts, look in the post ^^^ he is talking about, there is a pump or something that is larger

Sorry Kyle, I was probably in a bad mood when I wrote that last post. You get tired of people signing up to the forumn to ask things like, will my stock bottom end support 1,000 hp cause a Supra's will? and things of that nature. There are a couple guys that have hit that goal, it cost a lot of money and time, but you already made statment that that isn't an issue. All the guys at 300+ hp are running MTX's as far as I know, Soulcontroller however is running a high boost level and stil ATX (I think) so check out his posts. mcgyvr knows what he's talking about too, he's been in this game a long time, so pay attention to what he says.
Now if you are looking to spend money then I'd consider have your tranny parts, like the gears and what not, Cryotreated. This is supposed to increase fatigue strength by like 200% or so. If I could afford it I'd Cryotreat everything in my engine and tranny before I put it together (but Im poor :( ) Also consider a Redline or Royal Purple additive/fluid, I remember several posts talking about which is best but I don't remember the outcome. Id also consider throwing a Kevlar blanket or steel sheild over the tranny just in case the tranny decides it doesn't want to hold together. If it explodes you'll be much happier that you just have to replace the tranny and block instead of everything in the engine bay (and maybe your foot :whoa ). Plus you get to pop the hood and have one more thing there saying that you are indeed a bad-ass.
One more thing I would suggest thiking about though, if you're going to get into the 350hp range then you're not going to do it on the stock computer, you'll need a stand-alone fuel managment computer. Doing this is going to raise some problems with running your TCU at the same time, I was considering this with my MegaSquirt setup. Now is where I make the jump from 'kinda knows what he's talking about' to 'this guy is blowing words out of his butt', it's possible to hook a Neon tranny to our engine and I don;t believe it is computer controlled. I've heard speak of it being stronger as well. This may be an option to avoid screwing with trying to trick the ECU and TCU into thinking that they are in control of something they can't control. Someone help me out on this. I hope this helps.

Originally posted by Keith2172
Also consider a Redline or Royal Purple additive/fluid, I remember several posts talking about which is best but I don't remember the outcome.

NOOOOOOOOOO dont add a single thing besides the mopar anti foam and regular atf+3 or +4. (I believe the atf+4 already has the antifoam added to it.) IMO its best to run regualr atf+3 and thats it.

Originally posted by Keith2172
if you're going to get into the 350hp range then you're not going to do it on the stock computer, you'll need a stand-alone fuel managment computer.

BS, its totally possible to run 300+ on the stock computer. its been done...

Originally posted by Keith2172
it's possible to hook a Neon tranny to our engine and I don;t believe it is computer controlled. I've heard speak of it being stronger as well.

yes this is an option too, however I only recommend that for a track only vehical. gearing on that tranny is not really for the daily driver. oh and skip the cryotreatment too, its really not needed.

IMO build it with the list of parts above, add a stage 3 hahn turbo kit. with larger injectors, go to a wideband dyno and tune that sucker till your blue in the face. then replace whatever you break in the next few months with stronger parts and your good to go :)

I had no problems at 280-300hp with a stock computer and stock ATX tranny.

350hp might need a piggyback fuel controller and a spare ATX sitting around, but huge partslists ^ are overkill imo.

Get to where you start killing axles on a weekly basis, add even more power, THEN worry about the transmission.

looks like I am too timid, but I've never been where those guys are, so you know who to listen to :P Keep in mind Im adding a standalone fuel computer to a completly stock block N/A, so I'm just a little off.