fig3 shows a known resonance - type exhaust part 50 which is provided with a diffuser - cone unit 51 formed of a diffuser 52 , connecting part 53 and countercone 54 . reference numeral 55 indicates the inlet pipe and reference numeral 56 of the tail pipe of this known exhaust system with a stretched diffuser - cone unit 51 . the disadvantage is the relatively high amount of required space . the resonance - type exhaust part 1 according to the present invention is shown in fig1 and is provided with two diffuser - countercone units 2 , 3 . each diffuser - countercone unit 2 , 3 includes a diffuser 4 , 5 and a countercone 6 , 7 . a connecting part in the form of a first deflection arc 8 , 9 is provided between the diffuser outlet cross section 4 a , 5 a and the cone inlet cross section 6 a , 7 a , the connecting part having an angle of deflection of 180 ° ± 30 °. a second deflection arc 10 , 11 is provided in the initial zone of each diffuser 4 , 5 . a third deflection arc 12 , 13 is further arranged in the end zone of the countercone 6 , 7 . second deflection arc 10 , 11 and third deflection arc 12 , 13 are each provided with an angle of deflection of 180 ° ± 30 °. the angle of deflection is always defined by the change in direction of the central line 8 a , 9 a , 10 a , 11 a , 12 a , 13 a between inlet and outlet into the deflection arcs 8 , 9 , 10 , 11 , 12 , 13 . the central lines of the first deflection arcs 8 , 9 are designated with 8 a , 9 a , the central lines of the second deflection arcs 10 , 11 with 10 a , 11 a and the central lines of the third deflection arcs with 12 a , 13 a . the central lines 8 a , 9 a , 10 a , 11 a , 12 a and 13 a each form a first plane 8 b or 9 b , a second plane 10 b or 11 b and a third plane 12 b or 13 b . the second planes 10 b and 11 b and the third planes 12 b and 13 b are provided an arrangement which is inclined preferably by an angle of about 90 ° to the first plane 8 b . the second planes 10 b and 11 b are arranged approximately parallel to the third plane 12 b , 13 b . accordingly , the resonance - type exhaust part 1 is provided with at least four passes which are indicated by the arrows 14 , 15 a , 15 b , 16 a , 16 b and 17 in fig2 . the first pass of flow 14 is formed by a common end part 19 . as is shown in fig1 and 2 , the resonance part 1 is provided with two diffuser - cone units 2 , 3 which in respect of flow are switched in parallel and which are arranged symmetrically with respect to a central plane 20 . the diffuser - cone units 2 start out from the common inlet part 18 and open into the common end part 19 . the branch 21 of inlet part 18 and the opening 22 into the end part 19 are located in the zone of the central plane 20 . in the embodiment as shown in fig1 the two diffusers 4 , 5 , the inlet part 18 as well as the two deflection arcs 10 , 11 are formed by a diffuser insert 23 arranged as a deep - drawing part . the countercones 6 , 7 and the end part 19 are formed by a cone insert 24 arranged as a deep - drawing part . the flange facings 23 a and 24 a of the diffuser insert 23 and the cone insert 24 face one another and are mutually detachably connected , with a separating plate 25 being arranged between the diffuser insert 23 and the cone insert 24 . the second and third planes 10 b , 11 b , 12 b , 13 b are arranged approximately parallel to the flange facings 23 a and 24 a . the first planes 8 b and 9 b are arranged approximately parallel to the central plane 20 and normal to the flange facings 23 a , 24 a . the separating plate 25 partly separates the interior chambers of the diffusers 4 , 5 and the countercones 6 , 7 from one another and thus creates meander - like flow paths . all parts of the resonance part 1 are housed in one housing which consists of the input - side housing part 26 and the output - side housing part 27 . exhaust gases coming from engine flow through the inlet opening 28 in the input - side housing part 26 and through the inlet line 29 . the inlet line 29 is connected to the connection piece 30 of the diffuser insert 23 , thus allowing the exhaust gases to travel further through the inlet part 18 , the second deflection arcs 10 , 11 and into the diffusers 4 , 5 . from there the exhaust gases flow through the first deflection arcs 8 , 9 which are formed on the one part by the diffuser insert 23 and on the other part by the cone insert 24 , with respective pass - through windows 31 , 32 are passed through the separating plate 25 . the exhaust gases further reach the countercones 6 , 7 via the first deflection arcs 8 , 9 and further to the third deflection arcs 12 , 13 and to the opening 22 into the end piece 19 . the exhaust gases now leave the outlet cross section 19 a of the end part 19 and , by flowing around the diffuser - cone units 2 , 3 parallel to the central plane 20 , reach the outlet opening 33 of the output - side housing part 27 where they leave the resonance - type exhaust part 1 into the exhaust line not illustrated in further detail . flow baffle plates 34 can optionally be inserted in the zone of the deflection arcs 8 , 9 , 10 , 11 , 12 , 13 in order to favorably influence the flow . the baffle plates 34 can be fastened to the separating plate 25 , as is indicated by the broken lines in fig1 for the deflection arcs 12 , 13 for example . in order to achieve a favorable heat transmission , diffuser insert 23 , cone insert 24 and the separating plate 25 are preferably made of thin - walled sheet metal . it is further possible to arrange the diffusers 4 , 5 as double diffusers , with a secondary diffuser 4 ′ which has the same cross - sectional ratio between inlet and outlet and is made of sheet metal being each inserted between the diffusers 4 , 5 . it is also possible to provide parts of the resonance - type exhaust part 1 such as the diffuser insert 23 , cone insert 24 or the separating plate 25 with a catalytic coating . in addition or as an alternative , a metal carrier catalyst can be welded into the sheet metal parts or a ceramic catalyst can be inserted between the sheet metal parts . obviously , individual parts of the resonance - type exhaust system can be made of ceramics . in order to improve the exhaust gas quality it is possible to supply blower cooling air also in the zone of the end part 19 or in the zone of the output - side housing 27 . it is further possible , for the purpose of further sound reduction in the zone of the output - side housing part 27 , to provide a reflection plate 35 , as is indicated in fig1 with the broken line . the exhaust gas flows in this case through the apertures 36 of the reflection plate 35 into a reflection chamber 37 and leaves the housing part 27 through the output opening 33 a . the output opening 33 is omitted in this embodiment .