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Predator pipe/muffler recommendation

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bpoirier

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Where I race locally there is a new class starting up using the Predator engine on pump gas. We can use either Predator 69730 or the 60363. We can remove the fuel tank and governor and install a top plate. We must use the stock air box and carb. We also must only use 10.8lb valve springs. We can run any pipe/muffler combo.
What I'm asking you experts out there is what pipe/muffler combo would you use? Would you think a jet change be required depending on the combo and what jet would you recommend? We are geared to turn them 5600-5800rpms. I have one of each part number engine. Do you think one would be better than the other? Would the pipe/muffler and jetting be the same for both engines? Just trying to get a feel for where I need to be with this. Thanks for all your help.
 
The RLV 5438C header or ARC .930 3-stage J-pipe would be good. You'll likely need to oversize the header stud holes if your using a 69730 Predator. With stock air box, a .033 jet is about as big as you want to go on either one of those...
 
What's your track like?
The 60363 is a top end motor but will float the valves earlier than the 69730....probably 5500 rpm tops. Unless you've got a big track I like the .880 pipe for it's midrange power(I build my own but I've played with lots of pipe sizes and I keep coming back to my .880 for my track...first one I built LOL).
 
We run an 1/8 mile banked red clay track. You can flat foot it on a good night. Even when we lift it's only to get the kart to set. You never roll out of the throttle but half way.
 
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