Need suggestions: Cutting bumper for dual exhaust

victory · 05-12-08, 03:46

Here's my car now

Here's what i'm going for. Using those exact tips. Just pay attention to the exhaust as i'm not doing de-badging or a spoiler.

Now, i already have the drivers side exhaust hanger, picking up the pipes locally this week I have access to a set of templates for cutting and i have the bumper fascias on the way

Here's what i need to know:

What tool do you suggest for cutting the bumper and not making a mess of it? Last thing i want is to have to replace the bumper.

Secondly, do you know where i can find the correct paint for the fascias? I'm guessing i'll need a primer, whatever color grey that is and a clear. Spray would be nice.

Way2SSlow · 05-13-08, 04:07

Is the dual cut out bumper a factory option for that car? If it is, I'd probably try looking at a junkyard for a wrecked (in the front) car to pull it from. Then just have a body shop match it to your car and you're good to go. I cant really be of any help as far as actually cutting it and painting it yourself because sanding is as far as I foray into bodywork. Best of luck to ya with whatever you decide.

Accumulator · 05-13-08, 09:57

That's what I was thinking too..some bumpercovers are structurally different and if you just cut out the sections it wouldn't work out that well.

OTOH, maybe yours isn't like that and *would* be OK to cut

Maybe a rotary tool like a Dremel. I'd use a flex shaft and I'd tape the area of operation, marking the cutline on the tape.

Heh heh, is is one of those "hope the hand of God is on your shoulder" things IMO, I'd sure hate to botch it up.

Stanger'66 · 05-13-08, 12:07

Use one of those little airsaws, I think that would work best. This is the tool I am talking about. As for paint, if you aren't experienced in painting, just take it to the shop, can't be more than a few hundred.

victory · 05-13-08, 07:19

The one you're looking at in the pics was a DIY job, including the paint, so i can't see any reason why i couldn't pull it off. Just wondering if anyone here has done something like that.

SLP used to produce a limited edition regal with what they called the "GSX" trim, but they were rare. They did, however, sell the parts for the conversion and thats were the templates and fascias come from. I've seen at least a dozen other cars from my club where this was done, and I'm pretty sure most of them did the cutting and painting on their own.

The advice i got was after laying out and tracing the template as follows

Was to use a pair of tin snips....made me a bit nervous but i guess if you stay on the line the fascia should cover up a rough cut to an extent.

todd@bsaw · 05-14-08, 05:49

Tin snips would be good and they are made with different angles and elbows for doing curves.
I had made a cut-out for my exhaust using a Dremel and it worked just fine for me.

Accumulator · 05-14-08, 07:11

victory- Ah, OK, you should be able to do it then.

I do think I'd rather use a power tool than tinsnips, but that's just me.

victory · 05-14-08, 09:07

Tin snips worked great and actually made a pretty smooth, well rounded cut. Only problem is i have to drive around without the fascia until it gets here and i get it painted. Oh well, car can't look perfect 100% of the time.

Accumulator · 05-15-08, 11:07

victory- Glad to hear it worked out so well! Was the plastic easy to cut accurately with the snips?

victory · 05-15-08, 12:05

Quote:

Originally Posted by Accumulator

victory- Glad to hear it worked out so well! Was the plastic easy to cut accurately with the snips?

The bumper cover cut like butter. Tin snips were definitely a good recommendation. Take a look for yourself.

When the fascias come in, I'm ready for them. Paint prep, primer, storm grey metallic, clear.

For some reason autozone only stocked big cans of the storm grey and if i wanted a tiny can i'd have to order a case. No bother, it was only a buck more. Now i know i'll definitely have extra to spray into a cup and touch up that scratch on my passenger side door.

This is what i plan to use to attach the fascias to the bumper.

There's about a 1" lip on the fascias. Some people recommended 3m double sided tape, but, even if that does hold well, i don't want any kind of gap between the lip on the fascia and the surface of the bumper becaue it would always bother me. This stuff should hold strong, be flexible and resist heat pretty well. Figure i'll rough up both the lip of the fascia and the contact area on the bumper with sandpaper, prep, lay down a bead, press in place and not mess with it for at least 24 hours.

Here's the tips i'm getting welded on. Same as on the white buick i used as an example above.

304 stainless. Good deal at $100 for the set. Nice replicas of the Corsa's, which i cannot afford at $300-400.

Anyway, hopefully the addition of a second muffler in there will fix that boost stacking problem i was having and get the car ready for a slightly smaller supercharger pulley without an appreciable increase in noise ruining the sleeper aspect.

So, the guy who let me use his template said he'd help with the custom computer tuning in return for a full detail. Guy is running a full intercooled 12 second buick. I took him up on it.

Aurora40 · 05-15-08, 12:14

You cut the bumper before you got the inserts? What if they don't show up?

The exhaust will still just run down the one side, and then Y off to the other muffler? Is it more of an appearance upgrade?

victory · 05-15-08, 12:30

Quote:

Originally Posted by Aurora40

You cut the bumper before you got the inserts? What if they don't show up?

The exhaust will still just run down the one side, and then Y off to the other muffler? Is it more of an appearance upgrade?

Short answer: Done out of necessity. Yes they look better, but they also flow better.

Long Answer:

The inserts will be in early next week. They aren't particularly difficult to find and I ordered them from a reputable source. The templates are much harder to find and a local guy with one was only free wednesday this week so i just did it. Otherwise it would have messed up plans to pick up the pipes saturday. So the back bumper will look hacked for a week. I've seen worse.

Yes, it's still a y pipe, but the pipes aren't really the major restriction on these cars, it's the muffler. One fellow buick owner tested the backpressure at the rear O2 bung and found the stock grandma exhaust had 14psi and the GTP y-pipe only had 3psi. The mufflers have a little more growl to them, they're not much less restrictive individually, but there are two of them. Generally the GTP duals are said to flow well enough to about 300whp. You can get the same performance out of a single pipe, but you'd have to use a single, high flowing (loud) muffler as opposed to a pair of modest flowing (quiet) mufflers. Might be worth mentioning, that aside from keeping the car quiet as a sleeper, the 3800 exhaust note sounds like *** when you open it up. (example of loud exhaust on a 3800: YouTube - gtp drive by note the farty obnoxious droning)

Regardless, no one makes true duals for the w-body anyway, just larger y-pipes.

Stock, the single exhaust isn't a problem, but with minimal modding you get boost stacking quick. After an intake, an upgraded downpipe and a little computer tuning for more aggressive shift points, i saw spikes over 11PSI with a stock pulley in 60 degree weather. It should be 7-8psi. Fortunately, i wasn't getting any knock retard at that level, which tells me that after the exhaust upgrade, a smaller pulley shouldn't be a problem.