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Nostromo 14th March 2017 16:46

Who knows about exhausts?
So heres what I'm faced with:

Its not actually a picture of my car but its pretty much the same. So the manifold leads down to the right hand side of the cat, goes left, up and right into the backbox then back out and down the left to the tail pipe.

What I want to do is leave the cat in place, then bring a slightly larger bore pipe up, to the right, down and out and in so doing, deleting the backbox for a bit more noise.

Will I face any loss of power/torque?

Will I benefit at all from using a slightly larger bore pipe? The only reason for a larger bore is I guess less restriction and a more aesthetic/pleasing look where the tailpipe will exit.

Any help is much appreciated :icon_wink:

retro200 14th March 2017 17:27

hi nick hows it going just get a centre exit cat back exhaust from the usa swifty ds; got one for his and ive just got the same one for mine cost 212.00 his e bay user name is "gonefishing69" price is delivered inc taxes postage etc they clear the rear clam just right about half the weight of stock one too also not too loud nice deep tone, worth a look picks up revs a bit faster too. also fitted a de-cat stainless manifold from "toyosports" got rid of those nasty pre-cats.

Nostromo 14th March 2017 17:42

Hi Mick, I was after the original look with an exit on the right hand side. I'm not overly keen on the centre exit. Would you mind posting a picture of yours? I figured I'd be saving weight by removing the backbox.

retro200 14th March 2017 17:57

only other way i can think is is to get a small stainless universal silencer with inlet and exit at each end and some bends and pipe and weld one up from the cat back i had considered this for mine shouldnt be too difficult, i think you will still need a box of some sort otherwise it will be far too loud.

Nostromo 14th March 2017 19:28

I've always liked the look of the tenabe medallion which uses a proper backbox:

And then the use the janspeed mandrel bent and flared exhaust parts from ebay for the pipework.

I would still want to remove the main back box.

retro200 14th March 2017 19:56

im sure something like that could be made up without too much bother even easier if it exits on the right hand side

ozi jim 7th May 2017 04:28

Standard engines often require back pressure in the exhaust to help with the scavenge effect in the cylinder combustion cycle,
putting a larger pipe or removing the muffler may not always give you the results if you go to large or no restriction.
On my GT40 I removed the triple pass mufflers for a s/steel hotdog muffler to get a better note.
It shortened the system by 2 muffler lengths and it lost 15rwhp.
I made reducer cones to go on the outlet that clamped on at the dyno.
When I found the one that got the 15hp back I then welded a copy of that on the tail pipe.
It is a 2 1/4 system necked down to 2'' at the end ( a cone then 2" pipe).
You need to start with a figure.
You can do a standing or rolling start timed over distance if you dont want to pay for a dyno.
I have no doubt their is an app to do the same measure, my driftbox has a HP mode and it calculates HP.

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