1. WHP is wheel horsepower, compared to regular HP which is horsepower at the crank. Between the crank and the wheels is the transmission and differential, through which some horsepower is lost. Most car manufacturers quote HP at the crank, but most Supra guys use HP at the wheels. There's anywhere from a 15% to a 30% difference between the two numbers, so 600hp at the crank is a lot less than 600rwhp. I need to know which one you're shooting for before I can advise you. "super fast" really doesn't give me enough info - sorry.
2. I also need to know whether the Viper really has 520hp at the crank, or he has 520rwhp, or if he actually might have more than that and he's just stringing you (and other potential 'victim's for him) along. Many street racers will tell people they have a lot less than they really do, in order to have the advantage when race time comes, and the $ is laid down.
3. An aftermarket stereo system will definitely add some extra weight, especially if you go with big subwoofers and a fiberglass/MDF enclosure. The more weight you add, the slower it'll be. On the other hand, you can always add even more hp to the engine to compensate for the extra weight if having a great stereo is that important to you...which means a lot more total $ for the upgrades (i.e. the $ for the stereo AND the $ for the additional hp to compensate). Your choice.
4. I still need more info about what you mean by "street race". Do you mean from a dead stop, or from a roll on the highway. You need to do different things to the car depending on which you're talking about.
5. I plan to help you out as much as possible, and get you all of the info you need to do the upgrades. However, I'd ask that you please keep an open mind on everything that comes up here. The guys kind of do have a point - an upgraded Mkiv turbo can be a death-trap to even the most experienced driver. I am being totally honest with you when I say that I wouldn't even let Schumaker drive my Supra without a lot of coaching ahead of time. The guys here are really just trying to keep you alive, and keep your Supra in one piece - and I think that we can all agree that those are two very worthwhile objectives. :)

I don't know how much you paid, so I can't tell you if you wasted your $. Your Supra is beautiful though, and it looks to be in great shape.

roll on a highway yeah that works better rather than a dead stop although even say im at a red light and some guy comes up with a car and wants to race and ijust want to smoke them haha so thats what i basically meant and 600rwhp sounds good so yeah that one the viper dude bought the car for only 42,000$ so i cant imagine it being somethign outrageously amazing..but im pretty sure 520 at the crank

600rwhp is A LOT, close to 700 at the crank. I really, really dont think that would be too fun to drive if it is your daily driver. Different mods will make it more 'drivable' than others. definitely important if you drive this thing to work or something.

You'll need a pretty big budget for 600rwhp. This means a fuel system upgrade and a full single turbo upgrade. You'll likely also need wider rims & rubber to make sure that the power can be put to good use. Add in installation costs, the fact that you want it to continue to look great, tuning costs, some track time, race fuel, etc. and I'd say at least $15000 USD is a budget that could get you into the ballpark of what you're looking for. Please let me know if that's a completely unrealistic figure for your budget, and we'll scale back the rwhp until it fits with your budget. If that's not a problem, we'll start getting into the specifics.

haha yeah its daily drive and yeah dont work ne more lol just enjoying my car i paid 24,880$ for it i wish i had a list of the aftermarket mods but the guy didnt give me any things i could check and find otu what kind of suspesion, exhaust intercooler and stuff i have and let uknow and yeah 700 is too much haha i just want it to be faster even tho its super fast now cause eventually im gonna put on a top secret wide body kit and like a bunch of new things but i just bought it like a week or somethign ago haha got my first speeding ticket today too haha but i just want it to be a lil faster its so annoying when muscle cars come up to you and think there all good i've smoked every car i raced so far but i just like having more speed

no thats lower than i expected actually thats very realistic but thats just the engine mods and stuff im gonna need alot more for the interior and everything i dont have any gauges and stuff int here just a turbo timer theres a ecu system or whatever and stuff haha not really sure of what that is i never liked cars until i saw a supra and i just fell in love so now im startign to like them alot more and want to learn more in depth

no offense, but if your getting speeding tickets your probably doing something wrong. if you must, get a radar detector. but find a local track that you can drive at, you would probably enjoy it.

yeah tahts true i gotta get a radar and stuff soon enough like i asid i just bought it and im just slowly progressing from here its only goign to get better and also my speedometer only reads 180km/h? but im 100% sure it goes way faster than that i gotta get that all upgraded as well

you sure it isnt 180mph? i think thats what the speedos go to

naw it says 180km/h and i know im going the right speed cause of other cars next to me so yeah it might be a stock one from japan pretty sure