i have to get my coils/plugs/wires changed but was wondering if getting the bhr kit is a greater upgrade compared to oems? My enigine is making a knocking noise and i wanna replace them soon but i dont know if im damaging the engine by driving on bad plugs/coils etc... so i wanna know should i change it now using mazda parts or should/could i wait for a month to get the bhr kit.

also i got problems with my cat i think. ive been reading the threads about the cat problems but the thing is my dealership that i bought my car from always bs arounf these issues. like when my mounts went out they said it was nothing and turned out it was the mounts. They r hesitant to check it for me and im at 71000 miles so im close to going over the warranty. It smells like something is burning while i drive the car and when the car is off it continues to blow smoke for like 20-30 secs. When it starts up it sounds like its clogged because when i let it warm up after the engine is cold or when its parked it sounds like it sputters. Dont know but I just wanna know cuz im putting way too much money in this car and i just hate how the dealerships here in milwaukee dont want to help me.