I bought a used DC JDM 4-1 exhaust and the donut gasket for the cat. I could have swore my jdm cat was also 2.5" and that the two would have bolted up to each other, but when we were fitting it we found that the cat flange was 2.25" Anywho we decided to see if it would seal using the DC 4-1 donut, and even though the donut doesnt completelyfit into the cat flange, it goes in about half way BUT does make a good seal!!! I know now i have a bottle neck at cat and was wondering would i gain anything at all by getting the proper 2.5" cat. I can feel good mid range gains already on the butt dyno, especially over 5k rpm, and i'm figuring that the 2.5" cat wont release that much more, anyone running a similar set up?
When i was torquing back on the header bolts to the engine i broke the top left bolt I didnt want to have to take the whole thing off again, and besides i didnt have a new bolt to use anyway, so i tightened up the rest of the bolts and took the car out for a blast and the checked to see if i was getting any blowout at that corner where the bolt is missing and it seems to be fine, so my question...how easy/difficult is it to replace one of those bolts or seeing as its not blowing out should i just leave well enough alone???
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