Pag

iTrader: (3)

I have a uk spec blob eye wagon and I ordered a HKS silent hi power cat back system today and the guy said it will fit the car but he did say it's a 3" system. I sure the uk spec is 2 1/2" so how will this fit? I did mention this but they seemed sure it wont be a problem.

Anyone help?

craigo

iTrader: (1)

im astonished you bought without actually knowing yourself of the fit.....

Pag

iTrader: (3)

This is what puzzled me though, I did question that it's a uk spec car and I thought it was 2.5" but he said it will fit. and we are talking about sumo power here. not like they don't know there stuff?

And usefull replies please.

mjchantler

If he knows your system is standard 2.5", then hopefully your first piece of new pipework will have a 2.5" connector nearest the cat and a 3" at the other end to fit the backbox. These step up pipes are available and quite common.

Pag

iTrader: (3)

Thanks for that info. I would find it had to believe they would send me an exhaust knowing it wouldn't fit. but just want to put my mind at rest. still new to this scooby stuff!

mjchantler

I'd ring them first thing in the morning mate and ensure that you've got a 2.5>3" centre pipe before they ship it.

mnem1c

iTrader: (4)

Some 3" cat-back systems narrow to 2.5. The blitz Nur spec R is an example.

mjchantler

He doesn't want it narrowing as it goes back though. He needs 2.5" at the cat widening to 3" at the backbox joint.

Pag

iTrader: (3)

Or I could just replace the whole lot in 3"? I will be decating at later date after all. I will bell them in the morning.

Cheers Guys.

mnem1c

iTrader: (4)

Thats what i meant. The system will be 3" but will narrow where it meets the down pipe. I think manufacturers do this to appeal to people with standard catted down pipes which are 2.5

Just check the spec. Simples

mjchantler

Agree. The centre pipe is one of the cheaper to replace anyway if you end up decatting and want a 3" straight through.

Pag

iTrader: (3)

Just one more thing, are fast flow sports cats any good? Depends on make of course but it will save the hassle for when the mot is due.

mnem1c

iTrader: (4)

Remember you lose compression (back pressure) with 3" systems. No point running a 3" system until your running 400bhp +

Pag

iTrader: (3)

Ok, Thanks for that. I do have a forged 2.1 engine but I understand that a wrx gearbox will only run about 400bhp max so would cost me a whole lot more £££ to go above that.

mnem1c

iTrader: (4)

6 speed box, 3" and deep pockets

Pag

iTrader: (3)

Don't I know it.

mjchantler

What he said. I wouldn't run a standard 5s WRX gearbox at 400hp. Play it safe around 350 max and expect a shorter lifespan, but at least it won't go bang.

You're not going to lose much back pressure (if any) with your 3" cat back system that you've just ordered.

craigo

iTrader: (1)

they know their stuff, im amazed you can hand over money without knowing your stuff.
see where im going.....

midnight

iTrader: (10)

The HKS hi power exhaust is a 3' system that bolts onto your std downpipe which is 2.5' .Quite a few 3' systems do this ,ie: blitz, miltec,etc so no need to worry,but at the same time they can connect to a 3' downpipe if required, you just use a 3'flat gasket instead of a 2.5' donut gasket.
Not all 3' systems will lose you back pressure , as I have just changed from a fully decatted 2.5' afterburner vortex to a 3' system with sports cat and the difference is like night & day.
Your std gearbox can 'let go' at 350 bhp so 400 it won't last long when the torque kicks in,so far better with a 6 speeder to be safe IMHO.

Pag

iTrader: (3)

Thanks for the replies.
Midnight, how do you find the sports cat? Not sure weather to go sports cat or full decat.

midnight

iTrader: (10)

Considering i have run a full decat for 18 months on a 2.5' system,i find the sportscat on a 3' system more responsive. I am seeing Bob rawle next week for a map tweak so will let you know.

Pag

iTrader: (3)

Thanks. I am interested. Pm me when you know.
Cheers.