E30 Exhaust

Hi all, the exhaust system on my UK 1990 320iSE has seen better days and needs renewing soon.
Currently it is the non-cat 3 part system with a mid-box and the single
outlet silencer. The question is whether I can install a 2 part system as a replacement without any adverse effects? According to the parts catalogue the 2 part system was fitted to some 320i cars, and the 325i. This seems to be a cheaper way to do it, and the rear valence is shaped to accept the twin outlets so it would be an attractive addition. Would there be any change to backpressure which could affect the engine? Also can anyone confirm whether the downpipe is the same for the two systems or would I need to replace this too?
Thanks for any advice. -- Mark
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I'd find your local powerflow agent. They'll make up a stainless system on the car from stock parts. I had one on my e30 318iS made four years ago for 300 GBP. Costs more than oem parts from euro car parts (only get the oem bits, their grade B stuff is tosh) but is guaranteed for as long as you own the car.
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Hi John. I did consider stainless as an option (Euro do some stainless versions of some OE parts) but not sure I can justify the extra outlay, given that the original mild steel components have lasted 16 years so pressumably the replacements would too. I'm not looking for any kind of performance gains and want to retain the original exhaust note. I reckon the powerflow parts for mine would be more expensive than 300, allowing for 4 years' inflation and the fact that mine's a six cylinder.
Cheers
Mark
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Someone once told me, as long as you have a pipe on it, you will have backpressure. Hard to say whether this rule still applies if the pipe is 6" in diameter, but I doubt that this is the cause for your concern.
Don't know where in the UK it is best to have this kind of work done, but my 320i, 1987 model, has been running just fine with a freeflow exhaust (just over 2" in diameter) for the last 10 years. No offset silencers and no backpressure issues. It does not sound as refined though! If you don't like a drone, fit an offset silencer at the back.
MW

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Thanks for that. I'm looking to put an OE replacement on, rather than anything aftermarket, I want to maintain the original performance characteristics and exhaust note. Will be doing the work myself so only the only issue is selecting parts that will definitely fit and work.
Mark
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when i cam to replace just the rear box on my car, I fitted an OEM replacement. sorry, cant recall the manufaturer. however, it fitted perfectly, lined up correctly, sounds as quiet as ever, and looks very well made. the previous OEM box lasted 12 years.
keith
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Hi Keith, does your car have the three piece system with a centre box too? Is the replacement the single outlet type? The problem I've got is that the centre box is on the way out as well as the rear, so i could replace both with a single backbox from a two part system (which has the twin outlets), as with a 325i, but I'm not sure if the downpipes are the same. Any thoughts?
Many thanks
Mark
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Sorry mark.. cant help you there.... my comments were to the quality of OEM parts.
how far are you froom an exhaust centre? sometimes the guys there can be quite helpful.. if its a slow day they may even put it up on the ramp and let you have look and measure..
keith

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