325 and 320 exhausts

[Andros]

can anybody tell me what the difference between a 320 and 325 exhaust system, i am asking as i bought the cabby as a 320 and changed engine to 325 m20, the person that changed the engine put the complete 320 system back 0n i want to put the full 325 system on there as mine is a 2 piece 320 d0 i need the 325 manifold aswel as im unsure if the bores are different also my 320 0nly has the single pipe coming out back of car, and am i losing power by only having the 320 system on there? thanx for taking time to read and help.....

[Speedtouch]

I gather that the 320i has a smaller bore than the 325i system, so yes, you will lose some power if using it with a 325i engine, particularly if it's the single pipe system rather than the later twin-pipe 320i one.

[Grrrmachine]

From the Wiki:

"320i and 325i systems are interchangeable as long as they are of similar ages. In the BMW inventory, the centre sections of these two models are the same, and the pipe bore is identical; 45mm. However, on the 325i the rear exit pipes are 60mm compared to 45mm for the 320i; this has no impact on the performance of the system, since all other pipes are 45mm. "

http://www.e30zone.net/e30zonewiki/inde ... aust_Pipes

Having said that, a single-bore pipe on a 320i pre-dates any of the 325i engines, so it'll definitely be throttling your new lump.

[Andros]

when you say it will definitely be throttling your new lump what do you exactly mean sorry for being a bit thick lol and as you can see that from one of my replys some people say i am losing power i no for sure my down pipe is twin but then joins as single so if i want the upto date twin exit tail pipes i will still need to change the manifold am i wright ? my car is an 88 e reg pre facelift origanaly

[Andros]

the 325 engine i put in was out the same year car aswel

[Andros]

it would be easyer if somebody has got aa full 325 system and maifold so i can just swap it all?????