Any exhaust design experts out there?

I have tried to work out howe to design a new exhaust to my 1600 X-flow GT-spec car to replace the present one.

Today, temporary, I use part of the old standard manifold modified to accept a down pipe to the silencer outside the car. This seems however rather restrictive.

Looking on old posts and on different home pages have now brought me to a new level of confusement.

I believe the tuned total length of the 4-2-1 pipe should be meassured from exhaust valve to where the diamater of the last pipe is significantly larger, i.e ends or meet the silencer.

(There seems to be some different ideas about this to).

But how long would this tuned pipe length be ???

The car is for road use, maybe meaning exhaust tuned to peakat 4500-5000 rpm?

Howe have you who made your own exhasust done?

Proposals for total tube length?

/Hasse

see the xls in this thread