No, as long as they were working good before you changed plugs and did not break them while changing the plugs they will work fine.
About 105,000 miles.
You wanna wait at least 3 months to start stretching. You don't want to wear plastic plugs or tunnels but tapers are fine only because you don't wear them. Never leave a taper in after stretching because it'll make a thin spot in your lobe because of the uneven weight.
Just to let you know, people will take you more seriously if you say stretch instead of gauge. Obviously, your ears have to be pierced. Then you stretch up using tapers- you remove the tapers after stretching and put in plugs for long-term wear. You don't wear tapers because they thin out your lobes. You wait at least 2-3 months between each stretch from16ga to 8ga. Then you'll have to wait a while longer depending on what method you use to stretch. Once you hit 8ga, you have the option of taping. Its pretty simple, just look up the specific info on your own. Tapers aren't really effective beyond 2ga. Don't skip sizes and don't wear acrylic, wood, or bone until your lobes are completely healed. This is just basic info. Look up specific information and guidelines if you decide to go through with it.
About a half hour if you're mechanically inclined; an hour and change if you're not.
If you have long thin arms like me, then you should be able to change the plugs by removing the plastic fascia that is below the windshield wipers. That should give you just enough room to maneuver. No need to mess with the air intake. I successfully changed my plugs and wires this way, but do not start taking apart your wires and plugs until you are sure that you can reach all of them first! You will also need a socket wrench extender to get the plugs out.
In my 91 RS 305, I change the spark plugs working from underneath the car. The spark plugs are easier to see and get a 3/8 ratchet with long spark plug socket on from underneath. How can you do that? is quite imposible to remove it, is no space to do work ?
pull the coil packs off and get a long socket, or a long extension
Remove plug wires and you can then reach plugs using a long (8') extension and proper size deep well socket and a ratchet(of course).
for the plugs on the drivers side take out the airbox, the two plugs are easy to change with this removed, as for the otherside, its underneath the car with a long reach socket and small extention, it is a very fiddly job but both can be done with a bit of patience...........
you have to through the wheel wells to ge to spark plugs. use a long extenison and a spark scocket with a sweival built on to it. good lock
No.