de-cat again.

sorry if this has been covered a million times, How much is a mid-de cat pipe (fitted) and what will it alter? bhp, sound, or nothing.?? plus will it have any adverse affects on boost pressure. Basically is it worth just having de-cat on its own or is it gona cost wadds to make it good.????

TT steve.

I see you have a j-spec, normally it is recommended that you de-cat both cats and use a restrictor ring to put some backpressure back in the system.

Not sure about just removing the second cat, but anything that reduces the back pressure can raise the boost on a j-spec, more boost = more power. Just ensure you stay at 1.2bar or below for a decent turbo lifespan...

Search BPU or look in the FAQs.

so what about on a UK spec? im putting on a cat back. wanna decat as well. cant get boost control cause of insurance.

What about decat on a UK? You'd need a boost controller to up the boost if thats what you're thinking of.

boost controller aaaaaaaaaaaaaaa......... will 200 quid do it??

tt steve

do i need a restrictor ring aswel? and is there a boost control i could remove if i had a crash cause insurance wont let me have one

You mean restrictor? That you wont need because you have to have the conroller to get the boost UP, its not like the JDM models that need controlling/taming if you will.

Best be honest with insurance, who knows what sort of accident you could be involved in, for example if you're trapped in your car and cant remove anything or even disabled after and not able to to fiddle with your car! Whose to know what could happen.

Im putting the sports exhaust on but am aware this is not going to make too much of a difference. Do u know if it worth while de-cating? Is there no way to increase boost with out a boost controller?

this is getting a bit grim guys.

tt steve

boost controller aaaaaaaaaaaaaaa......... will 200 quid do it??

 

tt steve

Steve, you shouldn't need a boost controller on your J-spec, Bobbeh was talking about the UK Supra which is a little different.

Removing both cats on your J-spec should increase boost pressure significantly, as the cats are very restrictive. In most cases it is neccessary to fit a restrictor ring (simple plate with smaller hole in it) to keep the boost to below 1.2bar.

Before increasing boost you should check the condition of your intercooler, if it is in poor condition it may not be up to the job. You will also need to fit a boost gauge, so you can monitor things. You will probably also need cooler grade of spark plugs fitting, to prevent misfire at high boost.

To be on the safe side, it would also be a good idea to fit a higher flowing fuel pump (Walbro 255l/h or UK spec) and a new fuel filter (Toyota).

this is getting a bit grim guys.

 

tt steve

Steve, Bob is talking about the UK car, which needs a boost controller, your J-spec shouldn't.

Removing the cats on a UK Supra doesn't have the same effect, as removing them on a J-spec. On a UK Supra a boost controller is needed to raise the boost. On you J-spec removing the cats, will probably increase boost too much, which is why a restrictor ring in needed to bring the boost back down to a safe level.

i have just fitted both CW decat pipes and restrictor ring to my car

heres the story so far

i am now hitting .9 boost....my options are too increase the diameter of the restrictor ring to increase boost...in theory this seems good except that if i get the boost to 1.2 just now....when the cold weather comes along and i put the foot down...i could potentially see anything up to 1.5 with the dense cold air - definitely not good

2nd option is a boost controller as i can raise boost to a ceiling of 1.2 without it going higher...or should in theory!

the other option is as follows....get the first cat removed and fit an envy pipe - its about 3" diameter as opposed to CW 2 1/2"-....this raised my car to 1 bar with the 2nd cat still in- this also meant i still passed an MOT. I did however change the plugs as this small increase did mean i needed the platinum plugs (as described in a previous plug thread)

hope this helps

For some reason I thought it was the second cat that was the restrictive one, am I mistaken? What option are you going for Irvy?

For some reason I thought it was the second cat that was the restrictive one, am I mistaken? What option are you going for Irvy?

1st one nearest the engine is the most restrictive.

ok cheers! So with just that one removed the car can still pass an MOT?

some tests may pick it up. depends how good the second cat is, i dont know for sure but do apexi do a performance cat for the mid section?? ££??.

tt steve.