stupid question but would if you left off the exhaust and ran an open downpipe. I know it is ilegal. Has any one ever ran it this way on the street. How loud would it be and how much hp would you gain. I want to do this for track days but kinda wanna take it on the street every once and a while thanks for the info.
-Kelin

Well, I would say that the gains would be very good. If you run open downpipe, then that's eliminating your main cat as well as your entire catback exhaust.

So as for gains, I'd look at around 20-30RWHP gains from doing that.

As for the noise, it would be loud as hell. This is what you should invest in QTEC

What you want is the QTEC unit. How I'd install it is replace your main cat with this one and then when you go to the track, just flip the switch and then you'll run open downpipe.
You can do this on the street during racing if you wanted to.

And when you're done, you can simply flip the switch, and it goes back to using your stock catback.

The easiest way is to modify a test pipe and install the qtec there.

I don't drive a supra so I dont know how hard it is, but you could modify your downpipe to fit the QTEC.

Just take off your downpipe, bring that along with the QTEC unit and ask them to weld them together so that the QTEC unit is RIGHT before your main cat/test pipe.

Hope this helps, and enjoy the noise, hehe.

Tony

With just a Dp you are looking at around 20-30hp as 3kgt said but I dont think it would be wise to remove the exhasut till the downpipe it draws alot of attention because I think it might draw unwanted attention.

open dp is loud as shit. an electric cut out (from qtec or dhm) welded to an aftermarket dp and cat back is probably the best way to go. usually a cutout will gain 10-15whp on a car that already has no cats and a catback system.

Yeah...my 20-30RWHP was based on if you were running stock catback, stock main cat, and stock precats.

On vr4s, you can gut the precats as well as the main cat. Usually, doing that and upgrading/eliminating the catback will yield a max of 20-30RWHP but as mentioned, only 10-20RWHP on an already modifed exhaust setup.

Tony

i drive my supra with the apexi gt spec exhaust 3.75 pipping and the Tanabe 3 inch Dp. never got pulled for for my exhaust.

i would like to say because of TTC last night i got pulled over. got inspected under the hood and yeah =)

quote:

Originally posted by SupraDsHine:
i would like to say because of TTC last night i got pulled over. got inspected under the hood and yeah =)

pwnt . did you get cited?

i have hks downpipe and hks carbon ti and there's not a whole lot of difference from before and after the down pipe. but it won't pass the deci. test. it also doesn't sound too loud to the point where it bothers me inside the cabin.