hi on a 99 uk impreza i believe that there isnt a cat in the up pipe,i invested in a stainless up pipe as i thought there was,i dont want to pay for the fitting of it if its not worth while,im going for about 300 bhp,would i gain by having it fitted or shall i not bother and flog it on?do people normally replace up pipes on this model and is it common for the standard up pipes to start blowing under more boost etc? any info on this subject would be a great help as ive got an up pipe and dont know wether to have it fitted lol.

 

People usually change the uppipe when changing either the headers or turbo and want to match them as best they can. The only change your likely to see is (depending on the ID size uppipe) your boost threshold will move further up the rev range. The standard uppipe should not start blowing under more boost. If your still on the standard turbo but you want 300bhp then I would wait til the time comes when you swap the turbo and put the uppipe on then (maybe with some ported headers).

 

thanks for that,ive already got a vf35 to go on,but im not replacing headers,so would it be advisable to fit the up pipe aswell?

 

I really wouldnt bother. You will keep the fast spool of the vf35 on the stock uppipe. If the aftermarket uppipe you have is around 46-47mm ID and is a slip jointed one then yes I would stick it on at the same time as the turbo.

There are a few wright-ups in the projects section of similar mods.
https://www.scoobynet.com/projects-4...ting-mods.html
https://www.scoobynet.com/projects-4...on-fettle.html


Mike

 

cool,cheers,ive just measured id of uppipe and it is 47mm,it has a flexible piece in it,is that what u mean?it is not adjustable in length or anything like that,its all one piece.should i wrap it before fitting or should i not bother with any of it at all? lol.

 

yes definatley wrap it. However I wouldn't put a flexi joint uppipe in. They tend to split/break and can then lead to problems. I have seen one case where the flexi failed and blocked the uppipe!

A slip joint is demonstrated in post number 6 of the first link I sent you.

Mike