-----Original Message----- From: Steven M . Tucker [mailto:smtcapecod@arczip.com] Sent: Thursday, October 31, 2002 6:28 PM To: 928 Subject: [928] oh yeah Has anyone attempted to put S4 cats on older model? Any fitment issues or flow projections? From: Jim Bailey [jim@928intl.com] Sent: Friday, November 01, 2002 11:15 AM To: 928 Subject: [928] RE: oh yeah Sure they bolt right on ..... no problem and can use dualpipe 85 exhaust. Flow capacity ? MORE we have pushed about 400 HP through the "dual cats".. Jim Bailey 928 International Jim@928intl.com www.928intl.com (714)632-9288 -----Original Message----- From: Steven M . Tucker [mailto:smtcapecod@arczip.com] Sent: Thursday, October 31, 2002 6:49 PM To: 928 Subject: [928] cheap exhaust Anyone have any thoughts about the ability of a no-cat Borla system to handle flow from a stock 4.7 Euro? I'm not content with the high-flow system that I've pieced together. If the car weren't intended to be a daily summer driver I would be. I'm also contemplating switching from the manifolds on the car, which have an EGR port and therefore may be seventies vintage, to a pair from a 85/86 32V car to alleviate restrictions at that end. But no one has been able to tell me the extent of modifications that would be required, and/or whether they would bolt up to an early OEM no-cat 2 into 1 Y pipe. Or a set of S4 cats. Headers just aren't in the picture presently due to budget and the cumulative cost of my 'improvised' system and the 'fix' for it. Anyone with answers to these questions or thoughts, please send me a note. Thanks! From: Jim Bailey [mailto:jim@928intl.com] Sent: Friday, November 01, 2002 1:35 PM To: 928 Subject: [928] RE: cheap exhaust Steve , you just needed to ask the right people ... The 78-84 cast iron exhaust manifold is an ugly piece of work , how it managed to be used by Porsche is beyond my comprehension . It is a heavy rough casting with rather small internal passages ...nasty , nasty would be an embarrassment on a 49 Chevy truck engine . For the 1985 32 valve engine Porsche designed a lovely tubular stainless steel exhaust " header " manifold . It features a stepped design with the tubing size increasing as the pipes merge , a corrugated section for thermal expansion and nice heavy flanges (to limit exhaust leaks) with two holes to bolt to the 85-86 engine BUT it will with a slight bit of clearance of the holes bolt right on the 16 valve head ! The only problem is ....... the triangular flanges at the end back of the manifolds do not line up with the pipes which come up from the catalytic converter . The reason for this is the exhaust ports on the 16 valve head are not centered but offset the 32 valve port is centered . So bolt the 85-86 exhaust manifold to a 16 valve head and one side is too far forward and the other sits too far back ( both heads on a 928 are the same just flipped 180 degrees )so the up pipe to the triangular flange from cat pipes needs to be modified usually just extend one side by about 2 inches (especially easy if you are using a "Test pipe" or X pipe in place of the cat) . Note that the 87 > also has the same design BUT Porsche uses a three bolt flange to each exhaust port so these will not fit the 16 valve head . A quick aside .( Devek custom headers very cleverly have a 5 bolt flange and so Devek goes both ways ! ). Steve your subject line ( cheap exhaust ) really does not apply to the Porsche stainless manifolds which list for about $2,000 EACH new but being such high quality stainless you can get good used manifolds for $500 a set from us or often less on E-bay be sure it is 85-86 ! . One point to consider is that the 85-95 manifolds work very well and with an X pipe in place of the cat add about 30 HP for a 89 GT comparable to the reported gains of some aftermarket headers also running cat less ! The reason aftermarket headers work well on many cars including the 16 valve 928 is because the stock manifolds are so BAD . The 85-95 exhaust manifolds designed by one of the premier automotive design firms , Porsche , are quite good ! Using the 85-86 on the 16 valve engine give you a "stock " Porsche manifold that works well but without many of the negatives typical of many aftermarket headers ( ground clearance , fitment , exhaust leaks , limited life , obvious illegality ). Start making 500-700 HP and obviously you need to redesign the exhaust for the new task and it will no doubt be less efficient at making 300 HP !! Just another example of more / bigger may not be better ! Jim Bailey 928 International Jim@928intl.com www.928intl.com (714)632-9288