I'm trying to install a big brake kit from Stoptech, but I can only afford to get a front set...
I was wondering if it would be possible to "port" the stock front brake system and replace the rear brakes, since the front brakes are bigger than the rear.

 

Simple answer: no.

First, our rear calipers have the parking brake integrated into it so even if you do find a way to get the front calipers to safely bolt up on the rear, you would no longer have a parking brake. This is why the Stoptech rear kit for this car has 2 calipers per wheel; 1 hydraulic caliper for regular braking and 1 mechanical caliper for the parking brake.

Second, there's no way in the world you'd be able to maintain the stock brake bias since stock-for-stock, the piston in the front caliper is considerably larger than in the rear. You'd be sending a lot more braking force to the rear when compared to stock, which will not only increase your stopping distances but will also make the car that much less safe since you'll be more prone to locking up the rear brakes before the fronts, which, even with this car's stability controller, would be a very scary situation.

 

You do not need the rear BBK in order to a balanced brake bias. You can order only the front STOPTECH BBK. I'm not sure what you mean about "porting" though.

If you need a front BBK let me know. We have one in stock.

 

How much will that change the brake bias? Even with stock brakes, I recently changed the front brakes (the rears still looked like they had 5-10k to go) and just he combo of new front brakes and worn rears was creating a dive during braking. Changing the rear brakes fixed this. I would expect the same condition, if not worse, with a BBK front only.

Why not suggest that the OP save for the whole kit and do everything at once?

 

There are 2 different things in mention here: brake bias and brake friction. When you replaced your pads and rotors bias, obviously, wasn't changed since the stock calipers were still in use. What did change was your car's increased stopping ability due to the increased friction between the new pads and rotors when compared to their predecessors.

In terms of bias, if the pistons in a BBK's calipers are properly sized, bias won't be affected, ie.. even though the Stoptech's have 4 pistons versus the stock caliper's single piston, bias between the front and rear is very minimally affected. Since I put on my Stoptech's, I haven't been able to detect any difference in bias but friction and torque levels are way up.

Cost is the biggest factor in not doing the 4-wheel Stoptech kit; it's freaking expensive! The front kit can be had for about $1700 but the rear kit, by itself, is nearly twice that at around $3300 since each wheel has 2 calipers in order to keep the parking brake. It can be had without the parking brake calipers/brackets for like $2700 but then you'd have no parking brake. It's just not a cost effective option; I can honestly say that it's mostly for show.

 

The STOPTECH BBK is a balanced brake kit, which means that although there are 4 pistons, the overall piston size is similar to the stock piston size. Since there are 4 pistons pushing equally on all sides it performs better and the balance stays in place b/c the piston size is still basically the same. You do not need a rear kit to have brake balance. If you want maximum performance, then get the rear BBK but it's about $3k for that kit b/c it uses 2 sets of calipers per kit.