BPU (J-Spec) with stock exhaust.

Will it be possible for me to reach BPU levels of boost (18psi) with the OEM exhaust, simply by fitting a full 3" decat?

Call me a boring sod, but since getting this stock J-Spec motor, I'm seriously loving the quietness, and have decided to leave off the almost-new Greddy Power-Extreme II exhaust that I had on the UK car.

So, will it work?

p.s. yup.. these Jap cars are very nice I can't get over how drivable and 'springy' feeling it is off the no1 turbo. There's very little to notice from no2 though, but I'm comparing against a BPU UK car while this Jap car is completely stock.

If both cats are out, I don't see why not

Shuper. This is sounding good then

The stock suspension is sooooooo nice too

How sad am I?

It's not in need of lowering like my UK car was, and even though I tried for the softest aftermarket springs for that car, this new one with (I presume) stock facelift jap suspension is light years ahead in terms of comfort and umm.. everything!

did this work ?

Yes I think so. Stock exhaust quite restrictive though so I can't remember whether I left the restrictor ring off altogether or if it just needed making a lot larger. I've put the stock exhaust back on again now anyway, so I need to reassess the restrictor ring situation. The PE-II exhaust is for sale, even though I think it's the best balance of sound/sportyness in terms of aftermarket exhausts, I'm liking the refined sound/feel again. Missus is a bit upset, more so that I'm selling the exhaust off "her" car

so you reached 1.2 bar with stock exhaust then ? I may just do this is there any draw backs ?

I thought this would have increased the temps too much?

I thought this would have increased the temps too much?

Me too!

I thought this would have increased the temps too much?

Why? That logic suggests that the car had stinking hot EGT's with the Cat's in.

Because the back box is too much of a restriction and therefore EGTs go up.

Just what i'd read.

With no restrictor ring it may do. Production tolerances and all that. A quiet Supra is a rare thing these days, and very nice!

So chris would you advise this ? Would the EGT hold out ?

Probably

Because the back box is too much of a restriction and therefore EGTs go up.

 

Just what i'd read.

I've not experimented with a stock (cat back) exhaust system, but I fail to see how it can be worse than a nasty 2" restrictor ring which must have horrific flow characteristics.

A restrictor ring is far more restrictive then most exhaust components that people accuse of raising EGT's IMO.

good point, I may just try this but best get a EGT guage to see whats going on down there first

Here's a bit more reading: http://www.mkivsupra.net/vbb/showthread.php?t=149559&highlight=exhaust