I have no real world experience on your questions but will respond on what I have read and noticed from postings...
1. It has been reported that performance wise just going with/replacing the element to K&N versus going w/their performance intake has netted better results. It was reported that either the air entering the intake was more turbulent and possibly warmer w/the open performance intake.
2. PRL seems to be mentioned a lot as to what members are using/installing.
3. Borla makes a nice exhaust system for our Accord's. Magnaflow is another option.
4. Another tuner option would be KTuner.
Your order of upgrades seems to be on point. One thing I think I would do is do the downpipe, exhaust, tuner at one time and have it dyno tuned. Reason being that way only one dyno session would be needed if you prefer that over a canned tune.
1. It has been reported that performance wise just going with/replacing the element to K&N versus going w/their performance intake has netted better results. It was reported that either the air entering the intake was more turbulent and possibly warmer w/the open performance intake.
2. PRL seems to be mentioned a lot as to what members are using/installing.
3. Borla makes a nice exhaust system for our Accord's. Magnaflow is another option.
4. Another tuner option would be KTuner.
Your order of upgrades seems to be on point. One thing I think I would do is do the downpipe, exhaust, tuner at one time and have it dyno tuned. Reason being that way only one dyno session would be needed if you prefer that over a canned tune.
On a stock Accord regular gas is the recommended blend/octane value from Honda.... however even in stock form it's personal preference. There is probably data out there that says it's a waste of money but IMO it's the owner of that vehicle's money and if they feel that the car runs better or want to use premium that's their decision. Now.... when you do get the performance upgrades and have it tuned both Hondata & KTuners will recommend you use premium fuel.